Why do thousands of Arab and Afghan girls come to India for hymenoplasty before getting married?

Answer :- 

What is Hymenorrhaphy?

Hymenorrhaphy or hymen reconstruction surgery is the surgical restoration of the hymen. The term comes from the Greek words hymen meaning "membrane", and raphḗ meaning "suture". It is also known as hymenoplasty, although strictly this term would also include hymenotomy.
Such procedures are not generally regarded as part of mainstream gynecology, but are available from some plastic surgery centers, particularly in the USA, South Korea and Western Europe, generally as day surgery. The normal aim is to cause bleeding during post-nuptial intercourse, which in some cultures is considered proof of virginity.

So why Arab & Afghan (Muslim Girls) come to India for hymenoplasty? Because they could be killed by their families if it were discovered that they were not virgins on their wedding night. And of course the operation has to be done in a place where no one knows them, so that the information cannot get back to anyone back home. Apparently medical treatment in India is also inexpensive.

Source :- quora.com & wikipedia