Mohan Singh was born in 1905 into a family from the village of Dhamial in Rawalpindi district, taught Punjabi, and with Amrita Pritam and a few others made modern Punjabi poetry a serious literary form rather than an extension of the folk repertoire.
His collection Sawe Patar, 1936, is usually taken as the point at which Punjabi lyric poetry became modern. Kasumbhra and Adhwate followed.
He edited Panj Darya, a literary monthly, for decades, and it was the principal venue for Punjabi writing in the middle of the century.
His poem Kanak di Balli and his love poems are widely sung. His politics were of the left and his later work is explicitly so.
He is less read now than Shiv Kumar Batalvi and was the more important poet of the two in the development of the language.
Sawe Patar broke with the qissa and the devotional verse that had dominated Punjabi writing and used the language for personal and secular subjects in a modern form. Nearly every Punjabi poet after him worked in the space it opened.
He came east in 1947 and taught at several institutions, and he ran Panj Darya on very little money for most of its life.
He was associated with the Progressive Writers' Association and his later work carried that politics openly. He died in 1978.