The partition of India into India and Pakistan was the result of an indigenous Muslim demand to create a Muslim state. The British acceded to it, but it wasn't their idea. Similarly, the current division of the Arabian peninsula was not due to the British but to the local politics. It was not naturally a single country. As for the partition of Palestine, again, there had never in history been a state or even an administrative unit comprising mandate Palestine so there was no reason to create one on the dissolution of the Ottoman Empire. And of course a single state would not have allowed Jewish self-determination. There are some places where colonialism created unnatural boundaries, but this is a badly over-hyped meme. The fact is that people often want to be independent so as to express their national character and/or be independent of what they see as oppressors. This is especially common when empires are dissolved. The modern Middle East is due primarily to the dissolution of the Ottoman Empire, not to the choices of the European powers.