628★★★★★
Brahmagupta sets out rules for zero
In the Brāhmasphuṭasiddhānta, the Indian mathematician Brahmagupta gives the first known rules for arithmetic with zero and negative numbers.
Science· India
Events this year
Ongoing
c. 3rd century – c. 9th century★★★★★
Classic period of Maya civilization
Maya city-states such as Tikal, Palenque and Calakmul reach their height in architecture, writing, astronomy and calendrics.
CultureScience· Mexico, Guatemala, Honduras
c. 3rd century – c. 11th century★★★★★
The Ghana Empire in West Africa
The Soninke Ghana Empire (Wagadu) flourished in what is now Mauritania and Mali, growing rich from control of the trans-Saharan gold and salt trade.
DynastyEconomy· Mauritania, Mali