The masnavi that carries his name
Wikipedia's own account of him is a single unreferenced-feeling paragraph built almost entirely on one 2013 web article; it states that he "wrote 18 books during his lifetime of 77 years, and is especially remembered for his Saiful Maluk, a Punjabi poetic rendering of the traditional Arabic story of Prince Saiful Maluk" (Wikipedia, "Mian Muhammad Bakhsh", section "Poetic talents and works"). The poem itself supplies what the encyclopedia entry does not: a closing roll-call of the Punjabi poets who came before him. In Christopher Shackle's translation of those verses, quoted on the page, Bakhsh asks where that earlier company has gone — "Where now has that company gone, Muhammad? Look and take careful stock" — before naming Shaikh Farid, Sultan Bahu and Bulleh Shah in turn as the tradition he is placing himself inside (Wikipedia, "Mian Muhammad Bakhsh", quoting Saif ul Malūk via C. Shackle, "Punjabi Sufi Poetry from Farid to Farid", in Punjab Reconsidered, 2012).
The article dates the poem itself, not by convention but by the poet's own count: "Mīān Muhammad Bakhsh himself states in his magnum opus, Sayful Mulūk, that he completed the work in the month of Ramadan, 1279 AH (1863 AD), and that he was then thirty-three years of age" (Wikipedia, "Mian Muhammad Bakhsh", section "Early life", citing the APNA biography). That single sentence, written by Bakhsh into his own poem, is doing more evidentiary work in this record than anything else printed about him.
A birth year the sources disagree on, and a death recorded at his own shrine
The page records the disagreement plainly rather than smoothing it over: "Mahbūb 'Alī Faqīr Qādirī, in a biography printed as an appendix to the text of Sayful Mulūk gives the date as 1246 AH (1830 AD)... 1830 and 1843 are suggested in other works" — and it is only by working back from the poet's own line about finishing Saif ul-Muluk at thirty-three that the article concludes "he must have been born in 1829 or 1830" (Wikipedia, "Mian Muhammad Bakhsh", section "Early life"). A life whose start date survives only as an inference from a poem's closing boast is itself a fact about how thinly this figure is documented outside his own verse.
He died "on the 7th day of the Islamic month of Dhu al-Hijjah 1324 AH (1907 AD), and was buried in Khari Sharif, not far away from his spiritual great great grandfather, Damriyan Wali Sarkar. To this day many people visit his tomb with the intention of receiving spiritual blessings" (Wikipedia, "Mian Muhammad Bakhsh", section "Death and legacy"). Khari Sharif itself is described, on its own Wikipedia page, only as an agricultural area "located at a distance of 8 km south from the city of Mirpur" (Wikipedia, "Khari Sharif") — a shrine village whose own coordinates the encyclopedia does not print, so this record stands it on the map at Mirpur, the nearest place a source gives coordinates for.