These are provided as a starting point, not to discourage further questions, data, or debate.

"How did Thailand manage to preserve its independence throughout the Age of Imperialism while the more powerful Burmese and Sikh empires failed to do the same?" at https://www.reddit.com/r/AskHistorians/comments/5biy9a/how_did_thailand_manage_to_preserve_its/d9p1k3s/ . /u/Flocculencio provided a good and brief summary of Siam's diplomacy.

"How did Siam (Thailand) avoid colonization by Europeans?" at https://www.reddit.com/r/AskHistorians/comments/1dc20m/how_did_siam_thailand_avoid_colonization_by/ . /u/sterio wrote about nation-state building.