Where does the phrase "behind the wind" come from?

Question

In Millennium: A History of the Last Thousand Years, chapter 4 ("The World Behind the Wind"), the second-to-last sentence:

On the evidence of the events of the fifteenth century, in the world east of the Bay of Bengal—the world "behind the wind", as Arab navigators called it—China could have [...]

There's more to the sentence, but it's not relevant to this question. (it's about why China didn't end up conquering Europe)

The part I'm interested in is the "the world 'behind the wind', as Arab navigators called it". Where was this term first used? i.e. he quotes Arab navigators, but which one and when?

Answer 1

I can't answer when the term was first used but I can take a guess on why it was called that.

Arab sailors sailing the spice routes would have been dependent on the winds. Crossing the Indian Ocean, they would have experienced the prevailing winds, known as trade winds, blowing from the North East. So from the point of view of these Arab sailors, "the world east of the Bay of Bengal" would have been "behind the wind".