Part and parcel of islam is the reliance on captured slaves from eastern and central europe, for everything. Technical experts, language experts, soldiers, builders, artisans...
No one knows how many hundreds of thousands (millions?) of Europeans were captured and sold in the muslim slave markets.
One of Marie Antoinette's cousins was captured in the Mediterranean, sold in the slave market and eventually was mother to a Caliph...
That could be possible, but it does not explain how people on the upper levels of caste heirarchy also tend to have such features. Foreigners and slaves go as outcastes.
Besides, Muslim foreigners and their descendents would be Muslim, not Hindu, or Sikh. There are people with similar features where there has been barely any, if at all, foreign influence. The southern inlands, for example.
All I want to say is that this theory in the main article only “explains” one reason why skin could have gone pale, and the same reason fails when examined in cases in other regions.