My husband, who's studying Uyghur this summer, came home with the interesting tidbit that the word for rainbow in Uyghur and Kyrgyz is hasan-husan (or asan-uson) which are the names Uzbeks give to twin boys.* It appears from a google search and also after consulting our Dictionary of Turkic Languages (which is so vital here that it wasn't scanned) that Kyrgyz and Uyghur are the only two Turkic languages that use that term, although an Uyghur friend of ours here thought the word was Uzbek, not Uyghur.
We find there is a lot of mixing of Turkic languages in Tokmok. Kyrgyz is obviously the most commonly spoken Turkic language here, but there are also a large number of Uzbeks and Uyghurs. Most people say the Uyghurs in Tokmok are a lot like the Uzbeks and mostly speak Uzbek, but the Uyghur language is here too. Anyway, there is certainly a mixture of Kyrgyz, Uzbek, and Uyghur here.
Back to rainbows. I'm really curious why Kyrgyz and Uyghur are the only two Turkic languages that use this term (or if they really are). Several other Turkic languages appear to have borrowed the Arabic word, and Uzbek used kamalak. And I'm curious if there's a story behind the term too.
I'd love to know more if you can tell me more.
* In Uzbekistan, if you have twin boys, the older is named Hasan and the younger named Husan. Twin girls are named Fatima and Zuhra. If you have a boy and a girl, you'll either name them Hasan and Zuhra or Fatima and Husan (we happen to know a Fatima whose twin brother is named Husan). Fatimah Zahra (Arabic spelling- Fatima is pronounced with the stress on the middle syllable in Uzbek, instead of the first as in Arabic) was Muhammad's daughter who was married to Abu Talib. Hasan and Husayn were their two living sons. Uzbeks aren't Shi'a, as you might expect from these names, but they are Sufi which explains the names. I haven't been able to determine if any other Central Asians or Turkic people use these names. And I don't know how prevalent the practice is in Uzbekistan either. And I don't know why Uzbeks split Fatimah's name into two parts. I believe that if the names are used in most Muslim countries, they're just for one person, not two.