I agree with you, the Unequal treaties that were forced on China , simply trying to enforce the flow of imports to the country, paved the way for future spheres of influence zones in China. The Dauguang Emperor , who ruled during the first and second Opium Wars, should not have enacted a heavy hand on Western imports as he did , which threatened the British military attache, and was used as a catalyst (the British refer to this as a defensive act on their commercial interests) to initiate the First Opium War.
The Dauguang Emperor should have shown more prudence, knowing the military mighty of the Europeans, and should have allowed a limited commercial treaty, whilst biding time to build the military defense and industrialization of China.
We, In Japan, were placed in the same position as China in 1850 when the American Naval Flotilla forced us, at gun point may i add, to either open our ports for trade or be subject to naval bombardment. These were the exact words of the American Commodore Matthew C. Perry. Thus led to the Treaty of Kanagawa, and thus led to Japan's almost fanatical speed of industrialization. The Meiji Government had, at that time, learned from the mistakes of his noble peer, the Dauguang Emperor, of the Great Qing Dynasty.
Do i think that the Unequal treaties and the Opium Wars were preventable? Absolutely, it was.
LOL. Bangkok? Oh my man, my man, don't go there. You have to visit Las Vegas !