Explanation:

Sonepur Cattle Fair is held on Kartik Poornima (the full moon day) over the months of November and December in Sonepur, Bihar, on the confluence of river Ganges(Gandak). It is also known as Harihar Kshetra Mela and it attracts visitors from all over Asia. To date, it is the biggest cattle fair in Asia and usually lasts from between fifteen days to one month in duration. It historically began when Chandragupta Maurya (340 - 297 BCE) bought elephants and horses across the river Ganges. The Sonepur Cattle Fair used to attract traders from places as far away as Central Asia. In 2018, the Fair started on the 21st of November and continued until the 22nd of December.