In the first place, there was internecine dissension and discord among the Sinhalese rulers. As a result, they became weak to the extent that they had to pay tribute to the Northern Kingdom.
In the second place, the fall of Polonnaruwa meant that irrigation tworks of the north central plain in the dry zone had to be abandoned and the area was left to develop into ajungle. This created a no-man's land, which became an effective barrier between the Kingdom of Jaffna and the Sinhalese kingdom.
In the third place, there was a vacuum of a competent imperial power during the period between the decline of the Cholas and the appearance of the Vijaya Nagara Empire.
In the fourth place, there was an influx of immigrants from South India to the only Tamil Kingdom in existence at the time, namely the Kingdom of Jaffna. This exodus took place, because
It may be appropriate to mention in this connection that whereas the settlers in Jaffna before the eleventh century are said to have come mostly from Kerala (Malabar), the immigrants of the Chola and Vijaya Nagara periods seem to have come from the eastern part of South India.
In many ways, the period extenalng rrom me rouneemn lu ~ne sixteenth centuries may be characterized as the Golden Age of the Tamils of Jaffna.
The capital of the Kings of Jaffna was Nallur. They resided at Kopay and ruled directly over the entire Peninsula and the neighbouring Islands together with the Island of Mannar and a portion of the mainland. Other territories in the North and the East were administered by hereditary chiefs called Vanniyars who paid obeisance and tribute to the king.
Kings assumed the alternate throne names Segarajasekaran and Pararajasekaran, and used the epithets Singaiyariyan (Lord of Singaingar, the earlier capital of the Kingdom of Jaffna), Setukavalan (Guardian of Setu or Rameshavaram) and Gangainadan (belonging to the country of the Ganges).
Their emblems were a recumbent bull -nanthi-, a Saiva symbol, and the expression Setu, indicating the place of their origin, Rameshvaram. The term setu was also used as an expression of benediction. These two emblems were also designed on their coins.