The earliest Mizo people to enter the present Mizoram were known as Kukis, the second batch of Mizo immigrants were called New Kukis. The Lushais were the last of the Mizo tribes to migrate to the Lushai Hills. By the time they crossed the Tiau River bordering Myanmar, the descendants of Zahmuaka, who came to be known as the ruling Sailo clan, had proven their mettle as able and assertive chiefs. The traditional system of village administration, too, had been perfected. As the head of the village, the Chief or Lal allocated lands for cultivation, settled all disputes in the villages, fed and cared for the poor and offered shelter to anyone seeking refuge. The Mizo history in the 18th and 19th centuries is marked by many instances of tribal raids and retaliatory expeditions.