Wat Yang or the "Monastery of the Rubber Tree" is a vanished temple situated on Ayutthaya's city island outside the Historical Park in Pratu Chai sub-district.
As Wat Pa Sak and Wat Mae Nang Muk are located on the property of Ayutthaya Wittayalai School, we could deduct that Wat Yang once must have been standing somewhere in this area.
Phraya Boran Rachathanin's (PBR) map shows no (unknown) structures in the area located between the two canals being Khlong Pratu Jin and Khlong Pratu Thep Mi. We can conclude that either there were no traces anymore from this temple in PBR's period or that the drafter of the mid-19th century map wrongly indicated the position of this structure (in fact the mid-19th century map is far from being proportional).