The Treaty of Asurar Ali was concluded in 1639 between the Ahom kingdom and the Mughals mainly to establish which territorial boundary arrangement in Assam?

Introduction / Context:
The medieval history of Assam involved a long series of conflicts between the indigenous Ahom kingdom and external powers, especially the Mughal Empire. Various treaties were signed to mark truces, fix boundaries and regulate control over key regions. One important treaty is the Treaty of Asurar Ali, concluded in 1639. Competitive exams often test your knowledge of which river or territorial line was fixed by this treaty, because it illustrates how political boundaries in northeast India were negotiated during the Mughal period.

Given Data / Assumptions:

• The treaty is named Treaty of Asurar Ali and dated 1639.
• It involved the Ahom kingdom and the Mughal forces in Assam.
• We are asked what territorial arrangement the treaty established.
• The options mention various boundaries and foreign powers; only one reflects the historical reality.

Concept / Approach:
Historically, the Treaty of Asurar Ali followed conflicts between the Ahoms and the Mughals over control of western Assam, including the important region of Kamrup. This treaty fixed the Barnadi river as the boundary between the Mughal controlled territory to the west, particularly in the Kamrup area, and the Ahom kingdom to the east. Recognising this specific boundary is key to answering the question correctly. The British, French and Portuguese did not play the central role in this 1639 treaty, so options mentioning them can be eliminated.

Step-by-Step Solution:
Step 1: Recall that the Treaty of Asurar Ali was signed between the Ahom king and Mughal representatives after a series of battles in Assam. Step 2: Remember that the main purpose of the treaty was to mark a stable frontier between the two powers in the region of Kamrup and adjacent areas. Step 3: Identify that the Barnadi river was chosen as the boundary line, with Mughal control to the west and Ahom control to the east. Step 4: Examine the given options and note which one specifically refers to the Barnadi river and the boundary between Mughal territories and the Ahom kingdom. Step 5: Option A states this exact arrangement, so we select it as the correct answer.

Verification / Alternative check:
If you consult regional histories of Assam or detailed accounts of Mughal Ahom conflicts, you will find that the Treaty of Asurar Ali is repeatedly described as having fixed the Barnadi river as the boundary between the two powers. The treaty is seen as an important event that temporarily stabilised the frontier. There is no mention of British, French or Portuguese spheres in relation to this treaty, which confirms that only the Barnadi related boundary in Option A is historically accurate.

Why Other Options Are Wrong:
Defining the boundary between British held Bengal and the Ahom kingdom: In 1639, British political power in Bengal had not yet developed to the point of negotiating such treaties, so this is anachronistic. Granting Portuguese traders exclusive rights along the Brahmaputra river: Portuguese traders were active in parts of India but they were not the main party in the Treaty of Asurar Ali. Merging the Koch kingdom territories fully into the Ahom realm: While the Koch kingdom had its own history of relations with Ahoms and Mughals, this particular treaty did not focus on such a merger. Dividing Assam into separate British and French spheres of influence: This reflects much later colonial politics and has no relation to the 1639 Mughal Ahom treaty.

Common Pitfalls:
Students sometimes confuse different regional treaties, especially when several involve rivers and boundary settlements. Another common error is to assume that any treaty about boundaries must involve the British, because of their later dominance. Keeping a clear mental timeline is crucial: the Treaty of Asurar Ali belongs to the Mughal period and is specifically between the Mughals and the Ahom kingdom, with the Barnadi river as the key boundary marker.

Final Answer:
The Treaty of Asurar Ali in 1639 primarily established the Barnadi river as the boundary between the Mughal territories in Kamrup and the Ahom kingdom.