source: Roof tiles dating back to the Tang Dynasty with this symbol have been found west of the ancient city of Chang'an (modern-day Xian).
target: Roof tiles from the Tang Dynasty with this symbol have been found west of modern-day Xian.
references: Roof tiles from the Tang Dynasty with this symbol have been found west of modern-day Xian. Roof tiles with this symbol have been found going back to the Tang Dynasty.  They have been found west of the ancient city of Chang'an (modern-day Xian). Roof tiles from the Tang Dynasty with this symbol have been found near ancient Chang'an (modern-day Xian). Roof tiles from the Tang Dynasty with this symbol  have been found west of the ancient city of Chang'an which is Xian in modern days. Roof tiles from the Tang Dynasty have been found west of Chang'an. These roof tiles from the Tang Dynasty have been discovered west of Xian. There have been roof tiles found west of Xian. Xian used to be called Chang'an. The tiles are from the Tang Dynasty. Ancient roof tiles have been found with this symbol on them. Roof tiles from the Tang Dynasty with the marking were found west of the old city of Chang'an (modern-day Xian). Roof tiles from the Tang Dynasty with a  symbol have been found west of Chang'an (Xian).