Its name after a local temple, Wat Tha Phra, an ancient private temple. There is no obvious evidence of when temple was built or who built the place. It is only known that formerly the temple was called "Wat Ko" (วัดเกาะ), which means "island temple" since in those days it was surrounded by three waterways, namely Khlong Mon, Khlong Bangkok Yai, and Chao Phraya River. Later, its name was changed to "Wat Tha Phra" as today, because Luang Pho Kesorn, the sacred Buddha image of Ayutthaya period, floated along the water and reached the temple, hence the name Wat Tha Phra, which means "Buddha pier temple".
Soi Phet Kasem 4, also known as Soi Wat Sangkrachai is a shortcut to Soi Itsaraphap 21 on Itsaraphap Road near the foot of Charoenphat Bridge and Kudi Charoenphat.[2]