Historicity of the Bhagwa flag

Question

I know of Marathas and Rajputs using bhagwa flags as their official hoists, but is there some older (Puranic) legend in associating the bhagwa flag with Hinduism?

I'm very specific about the origin of the flag; I already know the symbolism behind the bhagwa color.

From Wikipedia:

The Bhagwa Jhanda (Hindi: भगवा ध्वज, "saffron flag", or Bhagwá Dhwaja) is a saffron color flag that has been used by a number of Hindu-oriented political entities in the history of India.

The flag historically served as the flag of the Marathas, "it is swallow-tailed and of a deep orange colour emblematic of the followers of Mahadeo."

Answer 1

I'm very specific about flag. I know about the symbolism of bhagwa color.

If you are only looking for the importance of flag in hinduism then yes they are important.

Many Gods are often associated with particular flags.They are described as having certain flags with specific symbols on them.

Following are few such examples.I have here used the gayatri mantras for several Deities:

Goddess Chamunda is depicted as having a flag with the symbol of "Pisacha" on it.

Om Pisacha Dhwajayai Vidmahe soola hastaya Dhimahi Tanno Kali Prachodayath.

Similarly Goddess Brahmi is described as having a flag with a swan(hamsa) symbol on it.

Om Hamsa Dhwajayai Vidmahe Kurcha Hastayai Dhimahi Tanno Brahmi Prachodayath.

Goddess Indrani is having an elephant(gaja) on her flag:

Om Gaja Dhwajayai Vidmahe Hastayai Dhimahi Tanno Indrani Prachodayath.

Maheswari-Having a flag with bull on it.

Om Vrisha Dhwajayai Vidmahe Marug Hastaya Dhimahi Tanno Roudri Prachodayath.

Similarly Goddess Varahi is having a Mahisha(buffalo) on her flag etc.

Each of the Navagrahas is also having a particular flag with certain special symbols on them :

Sun

Om Aswadwajaya Vidhmahe Pasa Hasthaya Dheemahe Thanno Surya Prachodayath.

Om, Let me meditate on the god who has a horse flag, Oh, God who holds the rope, give me higher intellect, And let Sun God illuminate my mind.

Moon

Om Padmadwajaya Vidhmahe Hema roopaya Dheemahe Thanno Chandra Prachodayath.

Om, Let me meditate on God who has lotus in his flag, Oh, God of golden colour, give me higher intellect, And let moon God illuminate my mind

Mars

Om veeradhwajaaya vidmahae vighna hastaaya dheemahi tanno bhouma prachodayaat

Om, Let me meditate on him who has hero in his flag, Oh, He who has power to solve problems, give me higher intellect, And let the son of earth God illuminate my mind.

Budha

Om gajadhwajaaya vidmahae sukha hastaaya dheemahi tanno budha: prachodayaat

Om, Let me meditate on him who has elephant in his flag, Oh, He who has power to grant pleasure, give me higher intellect, And let Budha illuminate my mind.

Guru(Jupiter)

Om vrishabadhwajaaya vidmahae kruni hastaaya dheemahi tanno guru: prachodayaat

Om, Let me meditate on him who has bull in his flag, Oh, He who has power to get things done, give me higher intellect, And let Guru illuminate my mind.

Shukra

Om aswadhwajaaya vidmahae dhanur hastaaya dheemahi tanno shukra: prachodayaat

Om, Let me meditate on him who has horse in his flag, Oh, He who has a bow in his hand, give me higher intellect, And let Shukra illuminate my mind.

Shani

Om kaakadhwajaaya vidmahae khadga hastaaya dheemahi tanno mandah: prachodayaat

Om, Let me meditate on him who has crow in his flag, Oh, He who has a sword in his hand, give me higher intellect, And let Saneeswara illuminate my mind.

Rahu

om naakadhwajaaya vidmahae padma hastaaya dheemahi tanno raahu: prachodayaat

Om, Let me meditate on him who has snake in his flag, Oh, He who has a lotus in his hand, give me higher intellect, And let Rahu illuminate my mind.

Kethu

om aswadhwajaaya vidmahae soola hastaaya dheemahi tanno ketu: prachodayaat

Om, Let me meditate on him who has horse in his flag, Oh, He who has a trident in his hand, give me higher intellect, And let Kethu illuminate my mind.

Answer 2

The flags of kings, in Ramayana and Mahabharata, were mentioned as having some symbol but not Bhagawa flag.

(i) kovidara (pomegranate) tree was mentioned on the flag of Bharata in Ramayana

एष वै सुमहान् श्रीमान् विटपी सम्प्रकाशते | विराजत्य् उद्गत स्कन्धः कोविदार ध्वजो रथे || २-९६-१८

"The gigantic and glorious tree with superb branches is shining over there prominently. The ensign bearing the device of a kovidara (pomegranate) tree is shining on that chariot."

(ii) kapi - monkey was mentioned on Arjuna's flag in Mahabharata,

It was the very car from which the lord Soma had vanquished the Danavas. Resplendent with beauty, it looked like an evening cloud reflecting the effulgence of the setting sun. It was furnished with an excellent flag-staff of golden colour and great beauty. And there sat upon that flag-staff a celestial ape of form fierce like that of a lion or a tiger.

In my view, the saffron colour flag might have been used by some kings after invasion of Muslim kings, whose flag's colour is generally Green.