i want to know the detail information regarding work visa for china to pakistani people ?

Dear Sir/Madam,
my name is mohsun and i am from pakistan. master degree holder , 13 months teaching experience, 4 years telemarketing experience, currently looking for teaching job in china. i have few friends in china who encourage me to apply for china for work. i now make a plan to go china for work. i have few chinese teacher and recuriter friends who told me some restrictions on pakistani people. please guide me how i can go to china for work under work visa or bussines visa ? i need to know the present policy by chinese government for pakistani people. one friend have a job for me and agree to send me invitation letter but i am worried that if i am not eligible then how i can go to china ? please guide me to get rid of this problem . you can also send me reply on my email id asap gmail.com|mohsin2229. thanx in advance