Here the track diverges [branches off] from the trunk line.
After that this language began to break up into several dialects.
分岐線｜a branch (line)
分岐点｜〔線路の〕a junction; 〔十字路〕a crossroads
That station was located at a junction (point).／The tracks branched off in various directions at that station.
He was standing at the 「turning point [crossroads] of his life.