In February 1958, King Hussein of Jordan and `Abd al-Ilāh proposed a union of Hāshimite monarchies to counter the recently formed Egyptian-Syrian union. The prime minister Nuri as-Said wanted Kuwait to be part of the proposed Arab-Hāshimite Union. Shaykh `Abd-Allāh as-Salīm, the ruler of Kuwait, was invited to Baghdad to discuss Kuwait’s future. This policy brought the government of Iraq into direct conflict with Britain, which did not want to grant independence to Kuwait. At that point, the monarchy found itself completely isolated. Nuri as-Said was able to contain the rising discontent only by resorting to even greater political oppression.
Until that time both Iraq and Jordan were ruled by Hashemites that were installed by the British. Iraq underwent many coups since its independence. Religious jockeying foe power as you put it. The Monarchs were Sunni and a large part of the population Shia.
The Palestinians sided with Iraq and even undermined the Kuwaitis. I remember the Kuwaiti propaganda about newborns. I believe Kuwait could take some of these Palestinians back under the Trump plan.
Let me point out that Jordan occupied Judea and Samaria in1948-1967 and has a large “palestinian ” population that is estimated as 65-75% of Jordan. Jordan is 78% of Palestine. In 1988 it revoked the citizenship of the Arabs of Judea & Samaria so it would only be fair that they relocate them back to Jordan. Most are currently classified as refugees . Not sure why or how.
In 1970 there was a coup by Arafat called Black September and Hussein fearing for his throne killed about 70,000 PLO members and expelled the rest. They went to Lebanon and set up a mini state there and started killing Christians , culminating into Sabra and Shatila as well as the Lebanese Civil War. Israel interceded on behalf of the Christians and set up a safe haven in South Lebanon. The PLO were sent packing to Tunisia.(this is a very condensed version) BTW. Israel signed a peace treaty with Gemayel that lasted a short time and was abrogated by Lebanon.