The Kashgar Grand Bazaar (Dabazha) (with exception of the Sunday Market) is the busiest part of the city. The market is a kind of agricultural market (Nongmao Shichang), that has expanded to include anything you can think of, inlcuding clothing, knives, and more.
As an expansion on the same theme, Kashgar is also home to a weekly Sunday Market (Xingqiri Shichang) that takes place on the northeastern outskirts of the city. Conservative estimates put that area at least 5,000 stalls that see traffic of around 100,000 people daily. The mixture of people of different ethnic backgrounds from all over Central Asia descending on Kashgar to trade and buy various wares give the market an incredible atmosphere, so it is worth braving the crowds. The goods available include pots and pans, clothing, utensils and knives, and even live animals such as donkeys, goats and horses.
Be cautious to protect yourself against pickpockets and bagslashers in these markets. It's quite easy to lose your passport and money in these crowded markets.