▁been ▁reported : ▁ 9 3 0 – 9 4 3 ▁AD , ▁ 9 2 6 ▁ ± ▁ 1 0 ▁AD , ▁ 9 4 5 – 9 6 0 ▁AD , ▁ 9 3 1 ▁ ± ▁ 1 0 ▁AD , ▁and ▁ 9 4 6 ▁ ± ▁ 6 ▁AD . ▁▁ 2 0 1 3 ▁ ▁w ig gle - match ing ▁d ating ▁ ▁X u ▁et ▁al ., ( 2 0 1 3 ) ▁reported ▁ 2 7 ▁best ▁w ig gle - match ▁dat ings ▁from ▁a ▁single ▁partially ▁char red ▁ 2 6 4 - year - old ▁tree , ▁which ▁is ▁ ▁Y in ▁et ▁al ., ( 2 0 1 2 ) ▁also ▁reported ▁ 8 2 ▁best ▁w ig gle - match ed ▁A MS ▁ ▁ages ▁of ▁samples ▁from ▁four ▁carbon ized ▁logs , ▁which ▁is ▁ 9 3 8 / 9 3 9 . ▁However , ▁the ▁result ▁of ▁X u ▁et ▁al . ▁( 2 0 1 3 ) ▁used ▁a ▁" reg ional ▁ ▁offset " ▁in ▁their ▁ages ▁to ▁decrease ▁the ▁error , ▁and ▁their ▁new ▁date ▁was ▁obtained ▁from ▁the ▁longer ▁tree - ring ▁sequence ▁with ▁the ▁higher ▁analyt ical ▁precision ▁of ▁ ± 2 5 ▁ ▁years , ▁on ▁a ▁ 2 6 0 - year ▁tree - ring ▁sequence ▁that ▁covers ▁three ▁consecutive ▁w igg les ▁around ▁A . D . ▁ 9 1 0 , ▁A . D . ▁ 7