Cotton

The first people to grow cotton for clothing and towels and sheets were the Harappan people in India, about 2500 BC. Cotton is mentioned in the Rig Veda, written about 600 BC in India. A little bit of cotton was also grown in Egypt, but it never became very important there. In the 400’s BC, a Greek historian, Herodotus, wrote that in India there were "trees growing wild, which produce a kind of wool better than Sheep’s wool in beauty and quality, which the Indians use for making their clothes".
Around this time, the Ajanta Cave carvings show that cotton growers in India had invented a roller machine to get the seeds out of the cotton. By the Guptan period, about 200 AD, the Indians made a good business of selling cotton as a luxury to the Parthians to their west and to the Chinese to their east. The Romans, further away, thought of cotton as an expensive luxury like silk. They had to buy it from Arabic or Parthian traders.
Soon afterwards in the 500's AD, the Sassanians were certainly growing cotton, at least at the city of Merv in their eastern possessions. The English word for cotton comes from the Arabic “qutun.” The establishment of the Islamic Empire in the late 600's AD gave a big push to cotton production, which spread westward across the Islamic Empire to North Africa and Spain (which also uses the Arabic word for cotton, "algodon").
And the Eastern Roman Empire also started growing cotton, by the 700's or so. In West Asia and northern Africa, poor people began wearing cotton clothing. But in Europe, cotton was still a very unusual luxury, imported from the Islamic empire. After about 1000 Italian traders brought a little more cotton to Europe, but still as a finished luxury product, not growing it in Europe.