Thailand
Thailand National Route 4 from Sa Dao to Phatthalung, then Route 41 to Chumphon, then Route 4 to Bangkok, then Route 338/Route 9 to Bang Pa-in, overlap with AH1 to Tak, then Route 1 to Mae Sai.
Sa Dao — Hat Yai — Bangkok — Bang Pa-in — Nakhon Sawan — Tak — Chiang Rai — Mae Sai
Read more about this topic: AH2