Here is an interesting map of Nepal provided by the UN Environment Programme (UNEP).  And, what they are saying about 2011:

Human trafficking in Nepal – Patterns

Year: 2011

Author: Riccardo Pravettoni, UNEP/GRID-Arendal

Maiti Nepal rescues an estimated 2,000 thousand girls each year, including children and women intercepted at borders and victims liberated from brothels and from various forms of abuse and exploitation. It provides them with education, protection and rehabilitation. Current estimates are that Maiti Nepal receives over 4,000 thousand reports of missing young women suspected of being abducted every year. The majority, an estimated 70%, are sold and forced into prostitution; the remaining 30% are sold for forced labour. Foreign destinations of the missing women include India, China, the Gulf and the Middle East.