Horses were first introduced to Egypt around 1700-1550 BC. The earliest remains found are from the Second Intermediate Period (1650 BC). They were first introduced to Egypt by one of their greatest enemies - The Hyksos.
The Hyksos brought something else with them too...the Chariot. Up until that point, no such thing existed in Egypt. They were fast, agile and deadly on the battlefield. The Egyptians didn’t stand a chance.
Many Egyptian armies were decimated by this new weapon. The Chariot was typically drawn by two horses, side by side. Archers could occupy the cart and reign fire down on their foe.
Horses became an important possession for the elite, especially for the Pharaoh. Ramesses II mentions his horses in the poem of Kadesh. He essentially says that they were instrumental in the defeat of his enemies. The Horses saved the day.
Tutankhamun was a keen charioteer. No less than six chariots were found in his tomb.
Chariots may have also caused his death.