The hill range that separates the state of Manipur from the state of Nagaland is know as:

1. Physiography of the Purvanchal (Eastern Hills) (basic)

Welcome to our first step in mastering the mountain ranges of India! To understand the Purvanchal (or Eastern Hills), we must first look at a dramatic geological event. As the Great Himalayas reach the northeastern corner of India, they don't just stop; they take a sharp, hairpin-like turn to the south. This is known as the syntaxial bend Majid Husain, Chapter 2, p. 17. Imagine a giant conveyor belt of mountains suddenly pivoting 90 degrees downward after crossing the Brahmaputra (Dihang) gorge in Arunachal Pradesh. This southward extension forms the Purvanchal.

Unlike the high, snow-capped peaks of the Greater Himalayas, the Purvanchal consists of medium-height hills primarily composed of strong sandstones (sedimentary rocks). These hills run as a series of nearly parallel ranges and narrow valleys, heavily draped in dense evergreen forests due to the high rainfall in this region NCERT Class IX, p. 10. In terms of orientation, while the main Himalayas run East-West, the Purvanchal ranges predominantly run North-South NCERT Class XI, p. 11.

The Purvanchal is not one single mountain but a collection of distinct regional hills. Let's look at the key players from North to South:

Hill Range	Primary Location / Significance
Patkai Bum	Arunachal Pradesh; forms the frontier with Myanmar.
Naga Hills	Nagaland; Saramati is its highest peak.
Manipur Hills	Manipur; surrounds the central Imphal basin.
Mizo Hills	Mizoram; formerly known as Lushai Hills.
Barail Range	Acts as a bridge/divider between Assam, Nagaland, and Manipur.

A fascinating detail for your notes: the Barail Range is particularly significant because it acts as the geographical divider between the states of Manipur and Nagaland Majid Husain, Chapter 2, p. 17. Furthermore, this entire mountain chain doesn't end at the coast; it continues under the sea and re-emerges as the Andaman and Nicobar Islands!

Sources: Geography of India (Majid Husain), Chapter 2: Physiography, p.17; Contemporary India-I, Geography Class IX NCERT, Physical Features of India, p.10; India Physical Environment, Geography Class XI NCERT, Structure and Physiography, p.11

2. Major North Eastern Ranges: Patkai, Naga, and Mizo (basic)

When we look at the far eastern edge of India, the Himalayas take a sharp southward turn after the Dihang gorge, forming a series of low hills known collectively as the Purvanchal or the Eastern Hills. Unlike the towering snow-clad peaks of the Great Himalayas, these ranges are characterized by moderate heights, narrow valleys, and incredibly dense subtropical forests NCERT Class IX, Physical Features of India, p.10. Understanding the North Eastern ranges requires looking at them as a sequence of north-to-south "parallel ridges" that define the international border between India and Myanmar.

The sequence begins in the north with the Patkai-Bum in Arunachal Pradesh, which forms the primary watershed between India and Myanmar. Moving southward, we encounter the Naga Hills. A critical geographical feature often overlooked is the Barail Range. While most Purvanchal ranges run north-south, the Barail Range acts as a massive physical barrier that separates the state of Nagaland from Manipur. It is also distinguished as the highest hill range in Assam, extending its arms into both Nagaland and Manipur Majid Husain, Physiography, p.17.

Further south, we find the Manipur Hills and the Mizo Hills (formerly known as the Lushai Hills). These ranges are not just geological features but dictate the very lifestyle of the people living there. For instance, while villages in Nagaland are often perched on flat hilltops for defense, the Lushai tribes of Mizoram traditionally built linear settlements along the ridges and valley roads Majid Husain, Settlements, p.10. To the east of these ranges lies the Arakan Yoma, a continuation of this mountain chain that stretches deep into Myanmar and eventually submerges into the ocean, only to reappear as the Andaman and Nicobar Islands Majid Husain, Physiography, p.17.

Range	Primary Location	Key Characteristic
Patkai-Bum	Arunachal Pradesh	Northernmost; India-Myanmar border.
Naga Hills	Nagaland	Home to Mount Saramati (highest peak).
Barail Range	Assam/Nagaland/Manipur	Divides Nagaland from Manipur.
Mizo Hills	Mizoram	Contains the "Blue Mountain" (Phawngpui).

Sources: Geography of India, Majid Husain, Physiography, p.17; CONTEMPORARY INDIA-I, NCERT Class IX, Physical Features of India, p.10; Geography of India, Majid Husain, Settlements, p.10

3. Drainage Systems of North East India (intermediate)

The drainage architecture of Northeast India is primarily defined by two massive systems: the Brahmaputra System and the Barak System. These rivers are classified as Major River Basins because their catchment areas exceed 20,000 sq. km INDIA PHYSICAL ENVIRONMENT (NCERT Class XI), Drainage System, p.19. While the Brahmaputra dominates the northern plains of Assam, the Barak system drains the southern hills. A critical geographic feature here is the Barail Range, which acts as a massive physical barrier and watershed, separating the states of Manipur and Nagaland and influencing the flow direction of these rivers Geography of India (Majid Husain), Physiography, p.17.

The Brahmaputra is notorious for its immense power, characterized by high discharge and frequent riverbank erosion. After entering India, it receives a complex network of tributaries categorized by their bank of entry:

Bank	Major Tributaries
Right Bank	Subansiri, Bhareli, Manas, Sankos, Tista, and Raidak
Left Bank	Dihang, Lohit, Burhi Dihang, Dhansiri, Kalang, and Kapili

The river reaches its peak annual discharge near Guwahati, moving over 2.5 million cusecs of water during the monsoon Geography of India (Majid Husain), The Drainage System of India, p.17.

Further south, the Barak River takes center stage. It rises from Mt. Japov in Nagaland and flows southwards into Manipur before making a sharp hair-pin bend. This system is unique because its basin includes Mawsynram and Cherrapunji, the wettest places on Earth. Consequently, despite being smaller than the Brahmaputra, the Barak carries a disproportionately heavy volume of water. As it enters Bangladesh, it splits into branches like the Surma and Kushiyara, eventually joining the Padma (Ganga) at Chandpur to be known as the Meghna Geography of India (Majid Husain), The Drainage System of India, p.18.

Sources: INDIA PHYSICAL ENVIRONMENT (NCERT Class XI), Drainage System, p.19; Geography of India (Majid Husain), The Drainage System of India, p.17-18; Geography of India (Majid Husain), Physiography, p.17

4. Inter-State and International Boundaries of the NE (intermediate)

To understand the North-East (NE) of India, we must look at it as a complex puzzle of high ridges and deep valleys. The region, often called the 'Seven Sisters' (Arunachal Pradesh, Assam, Nagaland, Manipur, Tripura, Mizoram, and Meghalaya) with Sikkim as their 'Brother', is connected to the rest of India by a precarious 22-kilometer-wide strip known as the Siliguri Corridor Politics in India since Independence, Regional Aspirations, p.126. Geographically, most of these states are defined by the Purvanchal (the Eastern Himalayas), which sweep southward from the Dihang gorge. These ranges, including the Patkai-Bum and the Naga Hills, don't just mark international borders; they dictate the very boundaries between our states.

While many people focus on the international frontier with Myanmar, the internal boundaries are equally fascinating. For instance, the Barail Range is a critical geographical feature. It is the highest hill range in Assam and serves as the natural divider between Manipur and Nagaland to the north, as well as between Manipur and the plains of Assam to the west Geography of India, Physiography, p.17. Because these terrains are so rugged and heavily forested, the boundaries have historically been hard to demarcate, leading to occasional territorial disputes between states like Manipur and Nagaland Geography of India, India–Political Aspects, p.55.

On the international front, the North-East serves as India's 'Gateway to South East Asia.' The Purvanchal mountains continue eastward into Myanmar as the Arakan Yoma. Crucial passes like the Pangsau Pass and Diphu Pass in Arunachal Pradesh historically connected India to Upper Myanmar and the Silk Road routes Geography of India, Physiography, p.17. Understanding these ranges is key to mastering the regional geopolitics, as the mountainous terrain facilitates both unique cultural identities and challenges like cross-border insurgency or smuggling Geography of India, India–Political Aspects, p.50.

Sources: Politics in India since Independence, Regional Aspirations, p.126; Geography of India, Physiography, p.17; Geography of India, India–Political Aspects, p.55; Geography of India, India–Political Aspects, p.50

5. The Barail Range: Connectivity and Divide (exam-level)

When we look at the Northeastern frontier of India, we often group everything under the umbrella term Purvanchal. However, to truly master the geography of this region, we must distinguish between the various ridges that define state boundaries. The Barail Range is the structural backbone of this area, acting as the highest hill range in Assam and extending its reach into both Nagaland and Manipur Geography of India, Majid Husain, Physiography, p.17.

The Barail Range is most significant for its role as a geographical divide. While the Patkai-Bum and the Naga Hills primarily form the international watershed between India and Myanmar, the Barail Hills perform an internal administrative and physical function: they are the specific range that separates the state of Manipur from Nagaland. To the west, this same range also acts as the barrier between Manipur and the Brahmaputra valley of Assam. This makes it a crucial pivot point connecting the Meghalaya Plateau in the west to the higher Eastern Himalayan chains in the east Geography of India, Majid Husain, Physiography, p.17.

Understanding the topography of the Barail Range also helps us understand the human geography of the Northeast. The rugged, heavily forested nature of these hills has historically dictated settlement patterns. For instance, in Nagaland, the difficulty of the terrain and the need for security led tribes to build villages on flat hilltops, spurs, and ridges at altitudes between 1000 and 2000 meters Geography of India, Majid Husain, Settlements, p.10. Connectivity through these ranges is limited to specific gaps and passes, such as the route joining Imphal in Manipur with Mandalay in Myanmar, which bypasses the steeper sections of the Purvanchal chains.

Range	Primary Role/Location
Barail Range	Divides Manipur from Nagaland and Assam; highest in Assam.
Naga Hills	Forms the watershed between India and Myanmar.
Arakan Yoma	Eastern border of Nagaland/Myanmar, extending south to the ocean.

Sources: Geography of India, Physiography, p.17; Geography of India, Settlements, p.10

6. Solving the Original PYQ (exam-level)

Now that you have mastered the sequence of the Purvanchal Hills, this question tests your ability to identify the precise 'inter-state hinges' rather than just the broad north-to-south alignment. You have learned that the Eastern Himalayas consist of several parallel and transverse ranges; the key to this question lies in recognizing the Barail Range as the structural bridge that connects the Naga Hills in the north to the Manipur Hills in the south, while also separating the Brahmaputra and Barak basins.

To arrive at the correct answer, use the spatial reasoning we discussed during your mapping sessions. While the Naga Hills and Manipur Hills are named after their respective states, the Barail Hills function as the actual physical boundary between Nagaland and Manipur. In your mind's eye, see the Barail range extending from the west (Assam) and pushing eastward to create the high-ground barrier that defines the border. Thus, the Barail Hills (C) is the correct answer. This range is also famous for being the highest in Assam, showing how one geological feature can serve multiple geographical roles.

UPSC often uses geographical proximity as a trap. For example, the Patkai Hills and Arakan Hills are common distractors because they are indeed part of the same mountain system; however, they primarily define the international border between India and Myanmar rather than internal state boundaries. Similarly, the Manipur Hills exist within the state itself, making them an illogical 'separator' for the state's own border. Recognizing these distinctions between internal and international boundaries is a classic skill required for the Preliminary exam. Geography of India by Majid Husain