Rugs come from almost every country in the world. Currently, the most popular manufacturing countries are Iran (Persian), Turkey, India, Pakistan, Afghanistan, Nepal and China (Tibet).
All of these countries have great manufacturers and not-so-great manufacturers. There is no steadfast correlation between country and rug quality.
There are however, some characteristics that are more common from one region to the next. The one that stands out is materials. More often than not, the wool that is predominantly used in Iran (as well as Caucasia) is far superior to that which is used in India or Pakistan. However, this can change region to region and weaver to weaver.