In a time long ago, when the centaurs were a very new race, they had a queen. Her name was Centauride, named after her father, Centaurus. She was the first female centaur, and a fair, noble, and beautiful leader, beloved by all the gods.
The god who loved her the most was Artemis, goddess of the forest. She gifted Centauride a beautiful golden crown with two willow branches dipped in the River Styx sprouting from either side, granting her immortality and eternal youth and fertility.
All the centaurs obeyed Centauride, expect for one. His name was Stag, and he was the most foolish and proud of all the centaurs. When he found out about the powers possessed in Centauride's crown, he wanted it for himself, so he stole it from her as she slept.
When Centauride woke and discovered that her crown was missing, she went looking for it and quickly found Stag boasting about his new treasure. Furious, but still upholding her honor, she challenged Stag to an archery competition. If Stag won, he would keep the crown and become king of the centaurs, but if Centauride won, she would regain her crown and Stag would be killed. He accepted. There was only one rule: Don't shoot your opponent.
Centauride got Artemis to agree to judge the competition, and so she arrived in the forest with her Hunters and hunting dogs. Stag knew that with Artemis, who much favored Centauride, judging, he would never win, so he stole Artemis's enchanted bow in the dead of night so he would win.
The next morning, both Artemis and Centauride quickly noticed that Stag had stolen Artemis's bow, but since neither of them had proof, they couldn't accuse him of it. They met in secret, and Artemis promised that because of his cheating, she would find a way for Centauride to win the competition.