you don't have to bring a lot of paper at a time.

There are a of ATMs in YI WU, you can open a bank account with ATM card, withdraw money whenever you need to.

Also, whenever I bought/ordered something which cost over 20000 RMB, I asked for merchant account number, then trasnfer money to the merchant. (I did bring a laptop with me so that I can transfer money from my bank account in China to merchants using my laptop)