The term "market" is flexible, and in Shanghai, it applies to vendors selling virtually the same thing all under one roof, or in one open section of space. Unlike the Western sense of competition, the Chinese believe that if you are all selling the same thing, you'll attract more customers. Fair enough.
Indeed, this makes life easy for the shopper. Want pearls? Go to the pearl market. Want fabric? Go to the fabric market. Want crickets? You guessed it, go to the cricket market. Just remember your bargaining skills! You'll need them in the markets of Shanghai.