B40 JANAM SĀKHĪ derives its name from the number attached to the manuscript in the catalogue of the India Office Library, London (MS. Panj B40). It consists of a unique collection of sākhīs or anecdotes concerning the life of Gurū Nānak, and, although it shares common sources with the PurātanandĀdi Sākhīāṅtraditions, it constructs a different sākhī sequence and incorporates a substantial block of stories which are to be found in none of the other major traditions. This cluster of anecdotes was evidently drawn from the oral tradition of the compiler's own area and includes all the principal janam sākhī forms such as narrative anecdote, narrative discourse, didactic discourse, and heterodox discourse. Another feature of particular interest and value is the inclusion of fifty-seven illustrations. The manuscript is also distinguished by the unusually clear description which is provided of its origins. Two notes appended to the manuscript (folios 84b, 230b) relate that the Janam Sākhī, commissioned by a patron named Saṅgū Mall and written in the hand of Dayā Rām Abrol and illustrated by Ālam Chand, a mason, was completed on Bhādoṅ sudī 3, 1790 Bk/ 31 August 1733. The manuscript is said to be a copy of some other now non-extant manuscript which might have originally been written subsequent to Gurū Tegh Bahādur's martyrdom (1675). This assumption is based on the fact that the manuscript makes no reference to Gurū Gobind Siṅgh or to his founding the Khālsā (1699) and historically the latest event to be mentioned is Gurū Tegh Bahādur's martyrdom. The manuscript comprises 231 folios (with five folios numbering 15-18 and 23 missing) and has two apocryphal works entitled Madīne dī Goṣṭi and Makke dī Goṣṭi conjointly entered under the title Makke Madīne dī Goṣṭi after the table of contents which follow the text. Since the entry on Goṣṭi is in a different ink and three more sheets have been added to complete the text of this Goṣṭi, it clearly is a later interpolation. According to internal evidence, the manuscript may have been recorded in Gujrāṅwālā district or near about although there is no clear indication about its provenance. Nothing is known of the manuscript's history since its completion in AD 1733 till 1907, although there is evidence which possibly indicates that the manuscript or a copy of it, may have been used in preparing Bhāī Santokh Siṅgh's Srī Gur Nānak Prakāsh. In 1885, Professor Gurmukh Siṅgh of Oriental College, Lahore, referred briefly and cryptically to a "Lahore Janam Sākhī" which had been recorded in 1790 Bk and in 1913 Karam Siṅgh historian, reported having once seen an illustrated Janam Sākhī' bearing the same date "in the possession of a Muslim bookseller of Lahore. " Both reports evidently refer to the B40 Janam Sākhī which had meanwhile found its way to London. There it was purchased in 1907 for 10 pounds by the India Office Library from its owner, Hāfiz 'Abd ur-Rahmān.

        At first sight the B40 manuscript appears to follow the Purātan tradition because its first eight sākhīs have been drawn from a source which presented its material in the characteristically Purātan style; the source appears, in fact, to have been the same manuscript as the Hāfizābād Janam Sākhī compiler used when recording his Purātan collection. From Sākhī 9 onwards, however, the B40 compiler chooses selectively from at least five different sources, four of them apparently in manuscript form and the fifth his local oral tradition. In addition to the manuscript which he shared with his Purātan analogue, he also shared a separate manuscript with the Ādi Sākhīāṅ compiler. A Miharbān source provided him with a small cluster near the end of his work and through the manuscript he has scattered six discourses of the heterodox variety.

        The narrative structure imposed by its compiler is, for the most part, a rudimentary one. It retains its consistency for as long as he remains with his first source (the first eight sākhīs), but little heed is paid thereafter to systematic order or chronology apart from the introduction of the death sākhī at the very end.

        The manuscript written in Gurmukhī script, has been edited by Piār Siṅgh and published under the title Janam Sākhī Srī Gurū Nānak Dev Jī (Amritsar, 1974). An English translation by W. H. McLeod has also been issued as The B40 Janam-Sakhi (Amritsar, 1979).