I was thinking that most likely the current Persian gulf would have been a valley during the ice age, with the Tigris and Euphrates meeting and surrounding the island of Dilmun and maybe a river from IRan and one from current Saudi arabia bringing the list of 4 rivers as in the Bible. These would have emptied into one common river that exited at the straits of Hormuz into the Arabian sea
Remember that conditions during an Ice Age are very arid/dry.