The collapse of mesopotamian society, like the collapse of later civilization, was caused

a constant invasions from foreigners
b a series of famines
c migrations of large groups to other countries
d tension between neighboring city-states

Who were the people that migrated south into india and indus valley

The rise of advertising in the 1920s. i am good with seeing how advertisements shape the roaring twenties and how it developed a new way of life through modern days. but i am not sure what the details of advertising in the 1920s were. if possible can you send me links (preferrably credential links) to sources that maybe show like the first company to start advertising through the radio, how advertising benefits (statistics graphs), etc.

What industry was exempt from the child-labor laws passed in the factory act of 1833?