The monsoon are experienced in the typical area roughly between 20degree nand 20 degree s. The mechanism of the monsoon depends upon the following factors :
1) the presence of high pressure over east of Madagascar. 
2)the soft of the position of itcz
3)the differential heating and cooling of land and water. 
4)the movement of westerly jet stream to the north himalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer. 
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one more point to the answer:-
one more pint to the answer:- 5. The intense heating of tibetan plateau.