- Alexander conquering China.
- Aforementioned Arab/Turkish conquest of Europe if not for Tours/Vienna
- Hideyoshi conquering China.
- Sweden wins at Poltava and negotiates peace in Moscow
- French Louisiana post-1803 becoming a French-speaking superpower
It's also worth noting that until the 1920's, "US invades Canada" scenarios necessarily become "US hands Britain commercial control of the Americas south of Mexico". Britain had the capacity to isolate the US, and would push to expand its informal Empire beyond the Southern Cone. It also requires the US to build up its pretty pathetic OTL army of 150k regulars into a force capable of conquering Canada and the British not noticing them doing this. At the time the British Army was 250k, without counting the small Canadian army and larger militia, or any colonial troops. This also discounts the Indian army, 140k served in Europe in WWI, though peace time strength was only 150k.
It is not ASB, exactly, but the US lightning attack on Canada requires exteme luck, British stupidity and a reckless disregard for the US's economic interests on the part of its leaders. It also requires the denial of every plausible continental port to the British with a few weeks, or the US will lose.
If the US is going to invade Canada, then they aren't going in with their post-ACW pre-WWII army. With US industrial capacity, by the 1890s the US could outbuild the British in all regards (Army, Navy, etc.). So I'd put this along the lines of China discovering and colonising America, in that it's technically possible and wouldn't really be a challenge, but no one has any reason to do so.
Confederate victory in the New Mexico campaign.
Implausible, but not as bad as "CSA conquers California".