The Air people are based on the San people of Southern African. The San people are distinctive for their lighter skin and their facial features which are typically associated with Asian phenotypes. However, we know that Original Man is the progenitor of all genetics.

The Earth people are based on the Hausa people in Nigeria and Niger.

The Fire people are based on Himba People of Namibia.  

The Water people are based on the Fula or Fulani people in the Sahel and West Africa.
 

Zulu Tribe in South Africa.

Shaka, the King of Zulu was a legendary warrior who brought together tribal factions in the Southern Africa creating a powerful state and identity, an identity which still exists today. The Zulu located in the south east of the continent were disorganized into clans before Shaka united them through his might. Legend has it, when confronted by a European Christian missionary, the missionary told Shaka if you don’t convert to Christianity you will burn in hell. Shaka replied saying around here on this land “WE EAT FIRE”.