The Reason for Blue Bana - Bansavalinama 
ਤਾਂ ਸੀਸ ਕੇਸ ਰਖ ਸਿਪਾਹੀ ਕਰਨੇ । ਕਟਿ ਸ਼ਾਸ਼ਤ੍ਰ ਬੰਧਵਾਇ ਸਿੰਘ ਨਾਮ ਧਰਨੇ ।
[And the Guru remarked], Adorning [unshorn] hair on your head, you shall be warriors, fastening weapons to your waist, and adopting Singh [Tiger] in your name.
ਮਾਤਾ ਕਾਲੀ ਦਾ ਬਾਣਾ ਨੀਲਾ ਪਹਿਰਾਵਣਾ ।
[You shall] wear the blue dress of Mata Kali [The Dark Goddess]
ਕਰਨਾ ਜੁਧ ਨਾਲਿ ਤੁਰਕਾਂ ਦੇ ਮਾਰਿ ਹਟਾਵਣਾ ।293।
Conducting war with the Turks you will kill and stop [their tyranny].
Bansāvalināmā, page 151, verse 292-293
Bansāvalināmā was written by Kesar Singh Chibbar, finalized in 1768 CE. The Chibbar family traces their family lineage back to Baba Gautham, who was a Sikh of Gūrū Nānak in the latter years of the Gūrū's life. Baba Gautham had three children, two sons being, Pairrā and Prāgā, and a daughter named Sarsuti.
Gautham's daughter [Sarsuti], had a son who was a teacher of Gūrū Gōbind Singh, and his brother Sanmukh Singh, was a warrior who received martyrdom at Chamkaur Sahib.
Pairrā was the father of Chaupā Singh, who was a playmate of Gūrū Gōbind Singh. Prāgā was a warrior in the time of Gūrū Hargōbind, and fought in the famous Ruhele Jang [battle], killing Chandu's son Karam Chand, and Kaane's son, Bhagvaane and the grandson Rattan Chand.
Prāgā's son, Davaarka Das had a son named Dargah Mal, who stayed in the congregation of Gūrū Hari Rai and Gūrū Har Krishan. The famous Bhai Mati Das and Sati Das were also from this lineage.
Dargah Mal's son was Bhai Dharam Chand, who stayed in the congregation of Gūrū Gōbind Singh.
Dharam Chand's son was Sardār Gurbaksh Singh, who under the orders of Mātā Sundari stayed with Bhai Mani Singh to run Harimandar Sahib in Amritsar Sāhib, this was around the year 1727-28.
It was Sardār Gurbaksh Singh's son who was the author of this book, Kesar Singh. Originally there were 8-10 small books that Kesar Singh wrote, but these were complied and finalized in 1768 CE under the title Bansāvalināmā.