As a general rule there was a commercial/export market for pile carpets much earlier than there was anything but a local market for flatweaves.
Sumac, Sumahk, Soumak, etc...
Supplementary weft wrapping most commonly over 2 back under one or over 3 under one. Many attribute the name to the city of Shemakha in Azerbaijani. Considered by many to be the origin of Sumac. While it is likely they wove Sumac there I think it is unlikely it stared there.
There is a variety of structures such as plain sumac, reverse sumac and countered sumac (see below).