Around 3000 years ago, some men became recognised as rajas by performing enormous sacrifices. The later rajas gained recognition by performing huge sacrifices. Ashvamedha or a horse sacrifice was an essential ritual for a raja. The rajas who performed significant sacrifices were then recognised as being rajas of janapadas rather than janas. The word janapada means the land where the jana set its foot and settled down. About 2500 years ago, some janapadas became more important than others and were known as mahajanapadas. Most mahajanapadas had a capital city, many of these were fortified, which means that huge walls of wood, brick or stone were built around them. To meet their requirement, they started collecting regular taxes. There were two significant changes in agriculture around mahajanapadas time. The growing use of iron ploughshares and People began transplanting paddy. Magadha became the most crucial mahajanapada in about 200 years. Many rivers such as the Ganga and Son flowed through Magadha which play an essential role for Transport, Water supplies and Making the land fertile. Vajji, with its capital at Vaishali (Bihar), was under a different form of government, known as gana or sangha. In a gana there were many rulers. Each one was known as a raja. These rajas performed rituals together. They also met in assemblies, and decided what had to be done and how, through discussion and debate.