The legend of Tha Tian started that Yak Wat Pho who guarded Wat Pho and Yak Wat Jaeng who guarded Wat Jaeng or Wat Arun which situated opposite Wat Pho, they were both close friends.
One day, yak Wat Pho was broke so he went across the Chao Phraya River to borrow money from Yak Wat Jaeng with an appointment date to return the money......On the deadline, Yak Wat Pho failed to pay, so after waiting for a long time, Yak Wat Jaeng decided to cross the Chao Phraya River to dun his friend.
Yak Wat Pho
However, Yak Wat Pho refused to pay, they had a quarrel and finally, the argument became a big fight....As they were huge and powerful, all trees and everything in that area wrer trampled and completely destroyed.
At last, the battle area was wipeout..... When Phra Isuan knew that the both Yaks brought trouble to humans and animals around there, he cursed them to become stone and ordered Yak Wat Pho to stand guarding in front of the hall ( Phra Ubosot ) of Wat Pho, and Yak Wat Jaeng to stand guarding the temple of Wat Jaeng. And the wipeout battle area which is a ferry, has been called " Tha Tian " ( Tha=ferry, Tian=flattened ) ever since.