Between 1928 and 1980 India won eight Olympic hockey golds. A very large share of the players came from a small area of the Doaba around Jalandhar.
The reasons usually given are the army, which played hockey and recruited heavily here; the mission and government schools that had grounds; and the village clubs and tournaments that gave continuous competition.
Sansarpur, a single village of a few thousand people, sent fourteen players to the Olympics across seven Games.
The decline is dated to the shift from grass to artificial turf in the 1970s. Astroturf changed the game to one of speed and short passing and required facilities that village clubs could not build. India had grass; the countries that could lay turf pulled away.
Punjab still supplies a large share of the Indian team. The nursery system that produced the golden era is gone and has not been replaced.
Sansarpur in Jalandhar district sent more players to Olympic hockey than any village anywhere, and the Doaba's other hockey villages are within a short distance of it.
The link was the army and the police, which recruited from these villages and ran the teams. A boy who played well had a job and a boy with a job kept playing.
The decline came with astroturf, which changed the game to one that needs a surface no village has, and with the collapse of the departmental team system that had paid the players.