Where did the Dothraki Come From? Culture & History - A Song of Ice and Fire - A Game of Thrones

My ultimate guide to Dothraki culture, religion, and history begins with the question "where did the Dothraki come from?" They do have an origin that predates their presence on the Dothraki sea, and to uncover it, we'll follow the twin trails of historical / physical evidence and religious / mythological evidence. Plenty of Essosi history, plenty of Dany and Drogo, and even Great Empire of the Dawn mythology included as well!