What influence did the aryans have on the people of indus valley ?

The Aryan have a big influence towards the Indus Valley People, which is the Dravidian. Before the Aryan came, the Dravidian has a very sophisticated technology that can be seen from the Mohenjo-Daro city which has sanitation system, etc. But, when the Aryan came with army they conquered the Indus Valley, and drove away the Dravidian. And the Aryan became the ruler of the Indus Valley. The Dravidian became slaves, etc. To maintain the purity of the Aryan, they create a cast system that divided the Indus Valley people into 4 major cast : Brahma (priest), Ksatria (King and Royals), Waisya (Traders), and Sudra ( Slaves, which is the Dravidian) 

Ifound this on google”the munich conference of 1938 was prompted by d. hitler's intention to take control of part of czechoslovakia. hitler sought to unite german-speaking people in a single nation and thus turned his sights on the sudetenland, a german-speaking region of czechoslovakia.” i hope it you