Maya cities were centered around temples used for ceremonial purposes and for observations of the stars, from which the Maya calculated mathematics and astronomy. Where were most of the later cities established?

Why did leaders such as siddhartha gautama abandon hinduism to createbuddhism around 500 bce:

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.

Lincoln fought to prevent secession from the united states of america. true or false?