Why it formed? Pan arab sentiment in syria was very strong. Nasser, leader of Egypt at the time, was a famous arab liberation figure after freeing egypt and telling the brits to fuck off the suez canal. This was actually the origin years of the Ba'ath party, a party defined by pan arab socialist nationalism (anti colonial nationalism in a socialist framework, not the guys you're thinking of). They were originally going to just do a chill economic federation (like the EU) but were very worried about the angry anglo screeching in the background and effectively just said "fuck it, one country".

for the split it was the usual culprits:

caused divisions because both countries had very strong communist parties and high level sympathies to them. There was no takeover effort ever planned, but their mere existence caused the US to go apeshit when the UAR formed in 1958. The terms of the UAR had actually made all political parties illegal, or absorbed into the new government party. They even dissolved their own Ba'ath parties. There was little threat. Nasser wasn't anti communist, he was just fine with dealing with the warsaw pact, but he just viewed it as not the ideology of the goal. Also if any coalition had been made, The Americans would have lost their minds immediately and would act as if they were the Arabian soviet union. They did want to fuck with the US, but not enough to be fucked by the US. But America didn't really care, they were going to be subversive anyway, but see if they could be turned to their side.

But then the big no no happened: The UAR nationalized their resources. All Banks, heavy industries, and even some light industry were all nationalized from foreign control.

The US lost their mind

America used their allies and terrorists in Jordan to cause conflicts, which they then blamed on Syria. Their new friend Israel did the same too. (funny story they couldn't find very many arabian allies, because they couldn't comprehend that arabians viewed zionism as far more dangerous than communism). This allowed them to put further economic and political pressure on them. In response, the UAR did more trade with the soviets. This confirmed in the US government's mind that this state was subverted into a communist state led by the international communist conspiracy.

They then used the CIA to exploit the new Union's instability by inflaming syrian nationalist parties, and with further border conflicts. Israel and the CIA then started using contacts within the Syrian military to launch a coup against the regional syrian government. Nasser and the UAR government were trying to do the best they can at maintaining the UAR, but were ousted, leaving only Egypt as the UAR until the 70s.

This was also the first victory of israel, its new enemy crippled in the region allowing it to pursue its colonialist agenda in attacking everything around it. The Six day war in 68 was their big push, annexing modern day israel and even the Sanai peninsula. The UAR was the last arab power in the region that had been able to defend the Palestinians, but this US funded imperialist expansion caused it to lose the last of its luster. A combination of military bribery and subversion caused the UAR to fall a few years later in 71. israel kept the sanai peninsula until 78, returning it to egypt.

The succession allowed the Gaza strip some autonomy, further solidified in the clinton negotiated Oslo accords. It is now the home of the Hamas militant group.

so uh that was what I could remember, hope its not text walling