Conversation so far:
What kind of sailing charts did Zheng He create?
Zheng He's sailing charts, the Mao Kun map, were published in a book entitled the Wubei Zhi.
Did Zheng He use his sailing charts to map out the ocean?
The Mao Kun Map covers the Indian Ocean including South India, Sri Lanka, the Maldives, and East Africa.

Question: Was he the first person to map this area?
Self-contained rewrite: Was Zheng He the first person to map the Indian Ocean?