
The Gregorian calendar based on Roman calendar, is similar to our present day Indian almanac - the Panchanga.
The Indian lunar year begins in the new moon of March - Ugadi.
Initially, the Roman calendar also marked the new year in March.
And they named the seventh month as September -Saptha-, the eighth as Ashta or October, the ninth as Nawa or November and the tenth as Dasha or December.
As a contrapposto, in India, there is evidence of January being marked as the first month of a year. Month of Mrgasirsha, or mid- December to mid-January, is referred to as Agrahayanam.
We can infer that in each land, people reckoned a month, as the transit of Sun in a zodiac sign.
- Shri Chandrashekarendra Saraswati, Kanchi