indeed a very good effort. This type ov essay mainly focus and depends on de following points.
The past, present, cause, impacts, remedies and conlusion; this is the first thing that examineer would like to see in ur essay and u have it all. I will try and figure ur essay out as under

The Goods
1) A very bried yet a powerfull history, mentioing kalashankov culture will surely leave a good impact on examiner.
2) Your essay seems to be in very good order and it went with a perfect flow.
3) Writen expression is simple and clear.

The Grey Areas
i wont really call thm de grey areas instead these are the thing that you will surely improve by the passage ov time.

1) While writting the main heading ov causes, impacts and solutions dont be that simple. Replace your words with synonyms like u can replace heading ov impacts with logical consiquences and solutions/remedies with Pragmatic Solutions.
2) While writing various causes in various heading ie social, regional effects; you should either be 3dimensional or 5 dimensional
3d = social, economic and political
5d = social, economic, political, religious and technological.
3) Quotations were missing, add relevant quatations where required.


Final Remarks
Overall an excellent effort and may Allah Almighty bless U