I need to apply Z visa

Hi I am Saiman, I had come to China for Business bt the company have offrd me good salary package & I had gone HK to APPLY bt they have rejected cos in Invitaion letter they mentioned need to apply from India. So I have the all documents from employer and I have done medical check up aslo in china .Kindly let me knw wre can I apply Z from India. & wt r the documents required rest of all above..?