Agrahayana

Agrahāyaṇa or Mārgaśīrṣa, (Hindi: 
अगहन - agahana; मार्गशीर्ष - Mārgaśirṣa) is a month of the Hindu calendar. In India's national civil calendar, "Agrahāyaṇa" is the ninth month of the year, beginning on 16 December 2020 and ending on 
13 January 2021. 
"Mārgaśīrṣa" means: related to "Mṛgaśiras" - the "Nakṣatra" (asterisms) known 
since Vedic times. 
In lunar religious calendars, Agrahāyaṇa may begin on either the new moon or the full moon around the same time of year, and is usually the 9th month of the year.
In solar religious calendars, Agrahāyaṇa/Maarkazhi begins with the Sun's entry into Sagittarius, and is the 9th month of the year.
Festivals.
Vaikuṇṭha Ekādaśī, the Ekādaśī (i.e. 11th lunar day) of this Mārgaśīṣa month, is celebrated also as "Mokṣadā Ekādaśī". The 10th Canto, 22nd Chapter of Bhāgavata Purāṇa, mentions young marriageable daughters (gopis) of the cowherd men of Gokula, worshiping Goddess Kātyāyanī and taking a vrata or vow, during the entire month of Mārgaśīṣa, the first month of the winter season (Śiśira), to get Śrī Kṛṣṇa as their husband.
Bhairava Ashtami falls on Krishna paksha Ashtami of this month of Mārgaśīṣa. On this day it is said that Lord Śiva appeared on earth in the fierce manifestation (avatāra) as Śrī Kālabhairava. This day is commemorated with special prayers and rituals.
In Odisha, all Thursdays in this month are celebrated as Manabasa Gurubara where in Goddess Lakshmi is worshipped by Hindu women.
In Tamil Nadu during this month of "Margazhi" ladies make "koolams" or "rangoli" early in the morning during 4 - 5 o' clock.