Explanation:

Sri Guru Har Krishan Sahib Ji (Gurmukhi: ???? ??? ???????) (Wednesday, 23 July 1656 - Saturday, 16 April 1664) was the eighth of the Ten human form Gurus (divine messengers) of Sikhism. He was the second son of the seventh Guru, Sri Guru Har Rai Sahib Ji and Mata Krishan Kaur Ji (Sulakhni Ji). Before passing away in 1661, Guru Har Rai Sahib Ji had declared that their younger son Har Krishan, would be the next Sikh Guru. Thus, Har Krishan Sahib ascended to the throne of Guruship on Sunday, 20 October 1661, at the young age of five years.
Today Delhi's Gurdwara Bangla Sahib, was constructed by Sardar Baghel Singh, the Sikh General who took control of Delhi, around the Princely Haveli of Raja Jai Singh, where Guru Harkrishan ji had stayed during his time in Delhi and death of Guru was commemorated in this Gurudwara.