In this case, as with the Esla and Pisuerga with the Duero, the Sil has flows larger than the Miño at the junction.

The Sil runs through the León districts of Babia, Laciana, El Bierzo and La Cabrera, and Ourense Valdeorras, among other locations across Villablino, Ponferrada, O Barco de Valdeorras, A Rúa, Quiroga and Ribas de Sil.

The river has been a rich source of alluvial gold, and was most extensively exploited during the Roman period, following the conquest of north-west Spain by Augustus in 25 BC.

It was extracted using hydraulic mining, involving the building of numerous aqueducts to expose and wash the alluvial formations.

According to Pokorny and to E. Bascuas, "Sil" would belong to the old European hydronymy, derived from the Indoeuropean root *sei- 'drip, run, humid'.