Shahe fen, linked to Pad Thai’s old name, is believed to have originated in the Guangzhou town of Shahe. The name combines Shahe, the place associated with the noodles, with fen, meaning rice flour or rice noodles in this culinary context.
Shahe fen are broad, white rice noodles with a slippery, elastic texture. They are commonly eaten fresh because they do not freeze or dry especially well. Cooks may cut them into strips or sheets and stir-fry them with meat and vegetables, as in Cantonese chow fun.
The noodles belong to the wider family of southern Chinese rice-noodle traditions. Similar flat noodles spread through Southeast Asia, where related forms appear in Vietnamese phở, Thai stir-fries, Cambodian dishes, and Malaysian or Singaporean cuisine. Similarity does not mean every regional noodle has exactly the same history or texture.
Shahe is now associated administratively with Tianhe District, but the historical place-name remains embedded in the noodle’s identity. That is why Shahe is the fair answer rather than Guangzhou, Guangdong, or a modern district name.