Gotra of Bheeshm and Paandav was Vyaaghrapaad of Vashishth line who was a seer of Rig Ved. Main king in their line whose year was being followed, is called Vyaaghramukh (i.e. head of that line). That was one of the 4 Agni Vansh joining hand under the king Shoodrak at Mount Aaboo in 756 BC (Shoodrak Shak era). They were Chaaphaani, Pratihaar, Paramaar, Chaalukya (Solankee or Saalunkhe). In Chaapahaani clan, the famous king Chaahamaan routed Assyria and its capital Nineve in 612 BC, which was marked by start of a Shak era. Thereafter, it was famous as Chauhaan - the last king of Chauhaan Vansh being Prithvee Raaj Chauhaan who was the last independent king of Delhi also. They were experts in archery or they were protectors of west border of India in shape of a Chaap (bow) called Maalavaa - like a garland (Maalaa). So, they were called Chapahaani. When Saraswatee river dried up, Hastinaapur was destroyed by Gangaa floods and the Paandav king Nichakshu - 8 generations after the Mahaabhaarat war, had to shift to Kosaambee.

Grandfather of Brahmgupt was the most famous king Anshuvarman (103-33 BC) of Nepal during whose time Vikramaaditya had started his Samvat at Pashupatinaath in 57 BC. Huensaang has described Anshuvarman as a king famous for knowledge who had written a book on grammar. By calculating time of Anshuvarman from start of Harsh Vardhan rule (605-646 AD), his time is calculated after Huensaang. (see Nepal Kings' lineage).

[some say that his father's name was Avantivarman of Nepaal (103-33 BC) in whose reign Vikramaaditya (82 BC-19 AD) started Vikram Samvat at Pashupati Naath, Kathmaandu.]

Jishnugupt was a famous astronomer, mentioned as contemporary by both Varaah Mihir and Kaalidaas. He made the latest version of Soorya Siddhaant necessary for starting Samvat. Jyotish Chakra (ecliptic) tied with Dhruv Taaraa (Polar star) is moving each moment since beginning. Ecliptic ending with Paush (Revatee Nakshatra) whose lord is P....) and starting with Ashwin Nakshatra were created by Brahmgupt along with planets. At the beginning of the Kalp, Chaitra Shukla Paksh, days, months, Yug and Kalp all started with sunrise at Lank.

In the same generation Paarshwanaath (the Jain Teerthankar No 23) was born in a ruling family of Kaashee. His Sanyaas time is called Jain -Yudhishthir - Shak of 2634 BC. That was the era of 100 years without rain (in Saraswatee River region) when Chaapahaani kings protected west border and saved people from famine. That has been called incarnation of Shaakambharee Devee in Durgaa Saptashatee, chapter 11. So, Chauhaan have been famous as belonging to Shaakambharee.

Brahmgupt has written many works on astronomy and mathematics, but he is well-known for his Brahm Sphoot Siddhaant (The Opening of the Universe). It contains 25 chapters and he writes in the book that he wrote it in Bhillamaal (modern Bhinmal) between the Multaan and Anhilwaaraa. It is 16 Yojan from Anhilwaaraa. Its first 10 chapters are on Indian mathematical astronomy - mean longitudes of the planets, true longitudes of the planets, Lunar eclipse, Solar eclipse, risings and settings, the Moon's crescent and shadow.

Its remaining 15 chapters seem to be the Addendum to the basic treatise. They are the additions to the Chapters 1, 2, 3, 4, 5, and 7; algebra, gnomon, on meters, on sphere, on instruments, and some tables. He defines Zero as the result of subtracting a number from itself saying "When a Zero is added to a number or subtracted from a number the number remains unchanged; and a number multiplied by Zero becomes Zero."

Its much material deals with Solar and Lunar eclipses and planetary conjunctions. He believed that the Earth was static and the year's duration was 365 days, 6 hours, 5 minutes and 19 seconds. He changed this value in his second book "Khand Khaandyak" to 365 days, 6 hours, 12 minutes and 36 seconds.

It is said that Brahmgupt also had abused Aaryabhatt with such adjectives as "Moorkhah" and "Pishaachah" for the simple reason that Aaryabhatt had claimed that the earth was rotating on its axis instead of being stationary in his Brahm Sphoot Siddhaant.

His another book is Khand Khaandyak, written in the year 665. He was 67 years old at that time. This book contains 8 chapters. Of particular interest to mathematicians in this second work by Brahmgupt is the interpolation formula he uses to compute values of sine.