Why do people revolt against their government??

What do the discoveries of shells used in jewelry and a huge dredged canal tell us about the indus valley civilization?

True or false plebeians were the highest social class in ancient rome

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.