Why, or how, did the kilt come about?

[MartinGrenoble]

...in the Highlands, there was no abundance of sheep. They are not indigenous to the Highlands and very few Highlanders kept sheep.

What could they have made their cloaks and blankets from, if there were no sheep?

Flimsy linen clothes cannot be compared with warm protective woolen goods, worn for different reasons. I cannot see how the loss of linen would increase thge use of wool. In cold climates, life without wool would have been very uncomfortable, and wool was complementary to linen.

Cloaks were probably universally worn/carried until a century or so ago.
The northern Brits were the only ones, as far as I know, that started pleating these lengths of cloth, belted them and eventually cut off the top half, producing a garment similar to the skirts (under whatever name) worn around the warmer parts of the world. Others preferred thicker woolen jackets and trousers.

Off topic : I wonder when women stated wearing skirts.

Martin

[MacMillan of Rathdown]

What could they have made their cloaks and blankets from, if there were no sheep?

I didn't say there were no sheep, just that there wasn't an abundance of sheep. Those sheep that were kept were sheared, and the fleece was spun into thread and woven into the fabric that became cloaks and blankets. One has to also remember that many a Highland bed was also covered in skins, as well as blankets, for warmth. Hide cloaks, with the hair still on, were also worn. In some respects the clothing of the Scottish Highlander was not all that dissimilar to the attire worn by other tribal peoples-- the American Indians.