Abu’l Fadl al Bayhaqi: Tarikh-i Bayhaqi
(History of Bayhaqi) (d1077) Persia
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Taken from: تاریخ بیهق جلد 1 by قزوینی، محمد ؛ بیهقی، علی بن زید ؛ بهمنیار، احم
https://www.noorlib.ir/View/en/Book/BookView/Image/13835/2/17?And=%D8%B2%D9%86%DA%AF%D8%A8%D8%A7%D8%B1

This chapter is famous for mentioning the provinces and the regions that are in the fourth quarter of the world.

(First) The Province of Zanj, which is called Zanzibar, and its two most important cities are called Sufala Al-Zanj (1) and Qanblah (2).

(Second) The land of Sudan is the ultimate place of the Maghreb. The biggest city is called Ghana. (Third) the country of Yemen ….

(1) the great city is called Sufalat al-Zanj: this is in error Sufala al Zanj was the place where the gold from Zimbabwe reached the shore; it was not a big city.

(2) Qanbalu: The island of Qanbalu from where the Zanj slaves were imported till the great Zanj revolt in Basra. (Zanzibar or Pemba).