Question

what is the main occupation of people in Nile valley region?

Answer 1

People in the rich Nile basins and related regions are exposed to a great of occupations viz.
Trade
Agriculture
Poltery
Farming
Yatching
Fishing, to name a few.

Answer 2

River Nile is the longest river in our world
The Nile Valley is surrounded by desert on both sides (Egypt region).
But it is also the most fertile region.
Most of the people living practice agriculture (almost 90%)
Agriculture is the main occupation in the Nile valley.
 See the green colour in yellow desert in given img. 
 all it is due to agriculture