Paging /u/i_like_jam.

I won't pretend to know the details of Kuwaiti history but where are you getting it that Basra was always more prosperous and independent than Kuwait? Basra was very firmly a part of the Ottoman empire, and an important port at that. I can't say how centralised and effective their rule was, or how autonomous Basra was, but they did rule the city. It was base of operations in their ears with the Portuguese for control of the Indian Ocean sea trade in the 16th century for example. During the First World War, Britain invaded the Ottoman Empire from India via sea, landing at Basra.

In the 1770s, when the Ottomans and Persians were at war (as they often were), the Persians successfully besieged and sacked Basra, taking control of it. Its population declined by the tens of thousands and its primacy as a port went contested - by Kuwait. Kuwait grew in this period as a result of Basra's decline. The British East India Trading Company, which was until the Ottoman-Persian war based in Basra, relocated to Kuwait at least temporarily as a result of its siege. The Ottoman-Persian war did not end until after the Ottomans had reconquered Basra. As for Basra's history between 1770s and 1914, I am less aware, but I would hazard a guess that the city eventually grew in prosperity after the loss of Egypt made it the Ottomans' last major Eastern port.

The Ottomans had a vilayet (province) of Basra, which they would sometimes merge with the vilayets of Mosul and Baghdad (forming a giant province with general territorial equivalence to modern Iraq). In the late 19th century, Basra province extended through southern Iraq and across the Gulf, down to Qatar. So Basra was always entrenched within the Ottoman system, and was considered their territory.

I mentioned WW1 before. During the war, the British took control of Ottomon Iraq through Basra, and when forming the mandate of Iraq after the war, they merged Basra province (minus the coastline from Kuwait to Qatar) with Baghdad and Mosul. This was not an easy process: the Kurds revolted in the north and the Shia in the south, and a 1920 uprising brought Sunnis and Shia together against the British. There is a clear sense that Basra was not an independent province. Things began to cool after the coronation of King Faisal I in 1921. King Faisal was an early adopter of pan-Arabism, which had the positive impact of drawing together the Arab Shia in the south, the Arab Sunnis in the centre, and the Baghdadi Arab Jews of the capital together, though at the cost of disenfranchising the Kurds in the north (which continued to be the most rebellious part of Iraq in the 1920s). It is no coincidence that the Iraqi ministry of education, which together with the Iraqi army was the main instiller of nationalism in early Iraq, was headed by Mohammad al-Jamali, an Arab Shia, and Sati' Al Husri, an Ottomanist-turned-Arab nationalist.

Kuwait was never a part of the Ottoman empire. The Bani Utub, the tribe who controlled Kuwait from around the 1710s, seem to me to have had an eye for profitable land. Kuwait has a good natural harbour and is well placed to divert trade from other ports, none more so than Basra. It also is rich in date palm trees, which before the discovery of oil was the major source of income for the Al Sabah. The Al Khalifa, the branch of the Bani Utub most involved in commerce, had a sizeable trade fleet. About 50 years after the founding of Kuwait they founded Zubara on the north western Qatari coast, from where they could capitalise on the pearl trade and divert shipping from Bahrain, just as Kuwait diverted trade from Basra. Again, it's that nose for profit which helped spur these city states' growth.

In 1899, Kuwait signed an agreement with Britain handing the British full control of its foreign policy. This effectively made Kuwait a part of the British empire, since Britain now had full control of Kuwait's relations with other states, notably the Ottomans. Britain had similar treaties across the Gulf, including Bahrain. While in some places (notably Bahrain), these treaties eventually led to ever-greater British encroachment on their domestic policy, in Kuwait I do not think it ever reached that extent. Kuwait remained in control of its economy (which essentially collapsed between WWI and the discovery of oil) and its governance (the British, to my knowledge, did not get involved in the 1938 parliamentary movement, for instance). In 1961, Kuwait achieved independence.

Since Kuwait could not enter into relations with other states between 1899 and 1961, I do not think it can be said to be a sovereign state. Yet, from the 1710s until 1899, it had an established autonomy from any other state (as I say, Kuwait isn't my speciality - there are probably periods where it paid tribute to the Saudis, Persians and Ottomans, but these would have been temporary pacts in which Kuwait did not surrender sovereignty). After 1899, the Al Sabah remained as rulers of Kuwait, at least nominally, and then more formally after 1938. And following independence in 1961, they continued as head of state in Kuwait and resumed control of their foreign relations (i.e. achieve full sovereignty). Thus, from the 1710s through to the present, there has been a direct continuity of first Bani Utub, and then Al Sabah, rulership of the islands. There is to my knowledge no such equivalence of historical independence in Basra's history.

As a final note, to make some of the terms used a bit clearer: of the Bani Utub tribal confederation, the Al Sabah quickly assumed governmental leadership in Kuwait. It is traditionally seen that the Al Sabah ruled Kuwait, the Al Khalifa monopolised its commerce, and the Al Jalahima acted as the military arm of the confederation. When in the 1760s the Al Khalifa and Al Jalahima migrated down to Qatar, the Al Sabah stayed on in Kuwait and achieved an (at least internally) uncontested position as the rulers of Kuwait.