What are the two most dominant economic activities in the arid climate of South Asia? Explain why.

I have read over all my notes, the section in the textbook dedicated to South Asia, looked at several maps indicating different factors, and Googled this question, but which two specific industries are dominant in arid South
Asia continues to elude me. I was thinking perhaps herding and trade, but I am not sure as there is no evidence to support me in what I've been given. Thank you for your help.

3 answers

http://www.geographynotes.com/essay/economic-activity-of-south-asia-agriculture-mineral-and-energy-resources/400
Seeing as how these folks pioneered seafaring in the Indian Ocean I would consider that an important part of their economic activities : http://www.cambridge.org/us/academic/subjects/archaeology/archaeology-asia-sub-saharan-africa-and-pacific/archaeology-seafaring-ancient-south-asia
Thank you very much!