What is the most ancient form of government?

A Monarchy

Explanation:

One of the first urban civilizations in the world was the Sumerians who established the world's first and oldest government, a Monarchy.

on november 6 and 7, 1917 (or october 24 and 25 on the julian calendar, which is why the event is often referred to as the october revolution), leftist revolutionaries led by bolshevik party leader vladimir lenin launched a nearly bloodless coup d'état against the duma's provisional government.