While Vijayabahu's victory and shifting of Kingdoms to the more strategic Polonnaruwa is considered significant, the real Polonnaruwa Hero of the history books is actually his grandson, Parakramabahu I. It was his reign that is considered the Golden Age of Polonnaruwa, when trade and agriculture flourished under the patronage of the King, who was adamant that no drop of water falling from the heavens was to be wasted, and each be used toward the development of the land; hence, irrigation systems far superior to those of the Anuradhapura Age were constructed during Parakramabahu's reign, systems which to this day supply the water necessary for paddy cultivation during the scorching dry season in the east of the country. The greatest of these systems, of course is the Parakrama Samudraya or the Sea of Parakrama, a tank so vast that it is often mistaken for the ocean. It is of such a width that it is impossible to stand upon one shore and view the other side, and it encircles the main city like a ribbon, being both a defensive border against intruders and the lifeline of the people in times of peace. The Kingdom of Polonnaruwa was completely self-sufficient during King Parakramabahu's reign.