Q: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
In what century was the first casual mention of the name Berbera?, Context: An Ancient Chinese document from the 9th century referred to the northern Somali coast — which was then called "Berbera" by Arab geographers in reference to the region's "Berber" (Cushitic) inhabitants — as Po-pa-li. The first clear written reference of the sobriquet Somali, however, dates back to the 15th century. During the wars between the Sultanate of Ifat based at Zeila and the Solomonic Dynasty, the Abyssinian Emperor had one of his court officials compose a hymn celebrating a military victory over the Sultan of Ifat's eponymous troops.
A:
9th