Birbal was the third child of his parents, the late Prof. Ruchi Ram Sahni and Shrimati Ishwar Devi. He was born on the 14th of November 1891, at Bhera, a small town in the Shahpur district, now a part of the West Punjab, and once a flourishing centre of trade, which had the distinction of an invasion by the iconoclast, Mahmud of Ghazni. The immediate interest that canters round Bhera is enhanced by the fact that this little town is situated not far from the Salt Range which may be described as a veritable "Museum of Geology ". Excursions to these barren ranges, where lie unmasked some of the most interesting episodes and landmarks of Indian geology, were often coordinated with visits to Bhera during our childhood, particularly to Khewra. Here occur certain plant-bearing formations concerning the geological age of which Birbal made important contributions in later years.
Bhera was his ancestral home, but his parents were at one time settled much farther a field, in fact at the reverie port of Dehra Ismail Khan on the Indus, and later migrated to Lahore.
Prof. Sahni's father was obliged to leave Dehra Ismail Khan owing to reverses of fortune and the death of our grandfather who was a leading citizen of the town. With the change of fortune, life became different and difficult. Undeterred, Ruchi Ram Sahni walked with a bundle of books on his back all the way from Dehra Ismail Khan to Jhang, a distance of over 150 miles, to join school. Later at Bhera and at Lahore, he distinguished himself as a scholar. He educated himself entirely on scholarships that he won. He was thus brought up in a hard school of life, and was entirely a self-made man.
Prof. Ruchi Ram Sahni was a person of liberal views, and during his career he became one of the leaders of the Brahmo Samaj movement in the Punjab, a progressive religious and social upsurge which had then freshly taken root. Undoubtedly father imbibed these ideas during his sojourn in Calcutta in his early days. He gave practical effect to his views by breaking away completely from caste. And when the call came, father, then a man of advanced years, stood knee-deep in the sacred mud of the tank of the Golden Temple and removed basket load of it upon his frail shoulders to assist in clearing the accumulated silt. His religion knew no boundaries. Always a patriot, he threw himself heart and soul into the struggle for independence and even tasted the severity of the bureaucratic baton at the Guru ka Bagh. He fought valiantly for the rights of his countrymen, and was more than once on the verge of arrest.
About 1922, when he returned the insignia of the title conferred upon him by the then government, Prof. Ruchi Ram Sahni was threatened with the termination of his pension, but his only answer was that he had thought out and foreseen all possible consequences of his action. He retained his pension !
It was inevitable that these events left their impress upon the family and were also imbibed by Birbal. If Birbal became a staunch supporter of the Congress movement, it was due in no small measure to father's living example. To this may be added the inspiration he derived, even if on rare-occasions, from the presence of political figures like Motilal Nehru, Gokhale, Srinivasa Shastri, Sarojini Naidu, Madan Mohan Malaviya and others who were guests at Ruchi Ram's Lahore house, situated near the Bradlaugh Hall which was then the hub of political activity in the Punjab.
Birbal's mother was a pious lady of more conservative views, whose one aim in life was to see that the children received the best possible education. Hers was a brave sacrifice, and together they managed to send five sons to British and European universities. Nor was the education of the daughters neglected in spite of opposition from orthodox relations, and Birbal's elder sister was one of the first women to graduate from the Punjab University.
Such then was the family and parental background which influenced Birbal throughout life. In later years he prided in calling himself a "chip of the old block" which he was in every sense of the term. It can be truly said that he inherited from father his intense patriotism, his love of science and outdoor life and the sterling qualities which made him stand unswervingly in the cause of the country, while he imbibed his generosity and his deep attachments from our unassuming and self-sacrificing mother.