The pig became a zodiac by his own efforts. On the day when the zodiac was arranged in the Heavenly Palace, the Jade Emperor stipulated that he must arrive at the Heavenly Palace to get it at a certain time. The first twelve animals to arrive are the Zodiac. The pig knew that he was stupid and walked slowly, so he got up in the middle of the night and hurried to queue up as a zodiac. Because of the long distance and many obstacles, the pig worked hard to climb to the worse gate, but the time for arranging the zodiac has passed. But the pig begged hard, and the other six animals also pleaded for it. Finally, the god was moved, and the pig was put into the worse gate and became the last zodiac. In this way, horses, cows, sheep, chickens, dogs and pigs have all become the human zodiac.