 The central Buddha of the Seokguram Grotto, a UNESCO World Heritage site, is recognized as one of the finest examples of Buddhist sculpture in eastern Asia.However, the political instability and weakened monarchy of the late 8th century seems to have had an effect on artisans as Buddhist sculpture began to become formulaic and lose vitality in the use of line and form.During the later days of Unified Silla, iron was substituted as a cheaper alternative to bronze and was used to cast many Buddhas and one can see regional characteristics creeping into the style of sculptures as local warlords and strongmen began to break away from the orbit of the royal family in Kumseong (now modern-day Gyeongju).