SARABLOH GRANTH, a poem narrating the mythological story of the gods and the demons, in ascribed to Guru Gobind Singh, and is therefore treated as a sacred scripture among certain sections of the Sikhs, particularly the Nihang Sikhs. The authorship is however questioned by researchers and scholars of Sikhism on several counts. First, the work is marked by extraordinary effusiveness and discursiveness of style over against the compactness characteristic of Guru Gobind Sirigh's compositions collected in the Dasam Granth. Qualitatively, too, the poetry of Sarabloh Granth does not match that of Guru Gobind Singh's Chandi Charttras and Var Durga Ki dealing with the same topic of wars between the gods and the demons. Profusion of metaphor and superb imagery of the latter compositions are missing here. Second, the author of Sarabloh Granth often uses his name, 'Das Gobind' or the phrase 'Das Gobind fatah satigur ki', which is generally contrary to the style- of Guru Gobind Sirigh. Third, the Sarabloh Granth contains, quite out of context, an account of the Sikh religion, which also includes a reference to the devolution of guruship on Guru Granth and Guru Panth (stanzas 3159-66). This would be out of place in a work of Guru Gobind Sirigh's own composition. Lastly, there is also a reference in it to Rup Dip Bhasha Pingal (stanza 2938/ 8), a work on prosody written by one Jaya Krishna in 1719, i.e. eleven years after the death of the Guru.
According to Pandit Tara Sirigh Narotam,a nineteenth century Sikh scholar and researcher, Sarabloh Granth is the work of Bhai Sukha Sihgh, a granthi or priest at Takht Harimandar Sahib at Patna Sahib, who however claimed that he had acquired its manuscript from an Udasi recluse living in a forest near Jagannath (Orissa).
Whatever its origin, the Granth became quite well-known and many hand-written copies of it exist. It is now available in printed form published in two parts by Baba Santa Singh, head of the Buddha Dal of Niharig Sikhs. It is a lengthy composition in a variety of metres, comprising totally 4361 stanzas (862 pages in print). The original source of the narrative is, according to the author (stanzas 2093, 3312.3409), Sukra Bhashya, an old classic of Hindu mythology. It is divided into five parts, part-I starting with a lengthy panegyric and invocation to goddess Sri Maya Lachhami, who is identified with Adi Bhavani (lit. Primordial Goddess), Durga, Jvala, Kali or Kalika, Chandl, as also with masculine Hari and Gopal. Among her myriad attributive names is also Sarabloh (lit. all-steel) which had been used by Guru Gobind Sihgh for Akal-Purakh, the Supreme God, in Akal Ustati. In part-II, Lord Visnu is entreated to become incarnate as Sarabloh (stanza 1167). But it is early in part V that it becomes clear that Sarabloh is an incarnation of Mahakal or Gopal, the Supreme Deity (stanza 2386).
The plot of Sarabloh Granth is almost identical with that of Chandl Charitras. The gods defeated by the demons approach the Goddess Bhavani who kills several demons including their chief Bhimanad during the 7-year long war. Later, Bhimanad's son.Viryanad, rises in power and wages war against the gods. This time Lord Visnu comes to their succour. Brahma and Siva also help ; but Viryanad not only remains unbeaten in the 12-year long war, but also captures the king of the gods, Indra, along with his sons. Visnu secures their release and leads them to Mahakal, who at their supplications appears as Sarabloh and afterfurther battles, fiercely fought, puts an end to Viryanad and his host. At this stage, the poet also describes the epic as a contest between reason and irrationality in which the former ultimately triumphs.

Article taken with courtesy from 'The Encyclopaedia of Sikhism' by Harbans Singh.

Note: Personally, I think that this granth possesses some Bani of Guru Gobind Singh but some of it has been added or concocted hence the authenticity of the granth is doubtful. (Kanwal)