The Sacred Monkey

In Ancient Egypt, hamadryas baboons (Papio hamadryas) were the sacred monkeys - they were chosen as the representatives of Thoth, the messenger of the Gods.  Thoth was also represented as an Ibis bird.

Hamadryas baboons are not native to Egypt, they are found in Somalia, Ethiopia, Erithrea, Saudi Arabia and Yemen.  How they got to Egypt is unclear. It is probable that they were imported from Nubia and then sold in Egypt as pets or to temples where they formed colonies.
Baboons were not only chosen as the representatives of Thoth, but also as representatives of the Sun God Re.  This could be due to the fact that baboons bark at the rising sun.
During the 26th Dynasty, sacred baboons were buried in the Ibis necropolis near Tuna-el-Gebel.  Some mummified baboons were also discovered by archeologists.