In school, and even at college level, most of the focus was on the Axis/Allies groups, what happened in Europe, Pearl Harbor being attacked, and some of the political and warfare history. But little was ever given to what was happening further to the SE (from Europe's perspective).
Was China or India involved in the war on either side? If they weren't involved, were they allied or leaning toward one side or another?
India was under British control and part of the allied forces. Burma, which had been until 1940 when the Japanese took Yangon, was part of India at that time as well. People from both sides of the India/Burma border were incredibly involved. In addition to regular soldiers fighting against the Japanese push into Myanmar and toward India, local Naga villagers were heavily exploited ("they helped us") to build roads through the jungle and otherwise guide the Allies through the region.
India was directly controlled by Britain at the time, and so also declared war on Nazi Germany in 1939. This was controversial in India at the time, and unfortunately I don't know enough to give you a good overview of it, but maybe if we have an India expert they can offer more information. My India knowledge is more or less limited to the Northeast. Regardless, India was officially at war starting in 1939.
Burma was also part of the British rule but again had largely fallen to the Japanese. I know you didn't ask about Burma specifically, but hey look it's part of India for a minute. Japanese occupation of Burma was brief, really only from 1942 to 1944 during which they devalued currency, forced their own form of rupees on (which you can still buy at any market in Yangon, fwiw), and basically mucked about. 75th anniversary of the fall of Yangon was just a few weeks back, actually.
From here on, the India-Burma was a big deal in the second world war, and one which Indians, Burmese and Chinese all played a large role.
Republican China meanwhile was active in that region as well, with a great many troops being sent into Burmah, many of whose descendants still remain, though with anti-Chinese sentiment being kinda a big problem in the 1960s, many have either nativised to a large extent, or moved to places like Taiwan which today still has a large number of people identifying basically as Chinese-Burmese-Taiwanese.
All of this is not even mentioning the fact that the second world war was in Asia actually the Second Sino-Japanese War, which formally began earlier in 1937, but actually actually began some five years before that. Fighting in Shanghai was going on in 1932, which wasn't the formal war but was a preview of what 1937 was to bring to the city and region. China was absolutely involved in WW2, much earlier than the US by any measure, because well before WW2 was WW2 to most anglophones, it was already well on it's way in Asia as the Second Sino-Japanese War, which also happened in the middle of the Chinese civil war.
Reading List:
The following are books I recommend, which you can pick from for whatever looks interesting.
Shanghai 1937: Stalingrad on the Yangtze by Harmsen, Peter
Burma Road The Epic Story of the China Burma India Theater in World War II by Donovan Webster
Forgotten Voices of Burma: The Second World War's Forgotten Conflict by Julian Thompson
China's War with Japan, 1937-1945: The Struggle for Survival by Rana Mitter
Forgotten Ally: China's World War II, 1937-1945 also by Rana Mitter
The Wars for Asia, 1911-1949 by Sarah Paine
I'll still come back and edit this some more. Sorry about that. Today turned out to be busier than I'd expected.