▁to ▁design ate ▁the ▁W an li ▁era ▁as ▁having ▁ended ▁in ▁the ▁sevent h ▁lun ar ▁month ▁of ▁ 1 6 2 0 , ▁while ▁the ▁Ta ich ang ▁era ▁sp anned ▁from ▁the ▁ 8 th ▁to ▁ 1 2 th ▁months ▁in ▁the ▁same ▁year . ▁The ▁T ian qi ▁era ▁officially ▁started ▁from ▁the ▁first ▁lun ar ▁month ▁of ▁ 1 6 2 1 . ▁ ▁From ▁a ▁historical ▁perspective , ▁the ▁Ta ich ang ▁Emperor ' s ▁reign ▁by ▁nature ▁of ▁its ▁short ▁time ▁span ▁amounts ▁to ▁nothing ▁more ▁than ▁a ▁foot note ▁in ▁M ing ▁history . ▁It ▁exposed ▁the ▁constitution al ▁weak ness ▁of ▁the ▁M ing ▁dynast y ' s ▁aut ocr atic ▁system ▁when ▁head ed ▁by ▁a ▁weak ▁em peror ▁as ▁typ ified ▁by ▁the ▁Ta ich ang ▁Emperor ▁and ▁his ▁successor , ▁the ▁T ian qi ▁Emperor . ▁From ▁the ▁limited ▁information ▁g lean ed ▁from ▁official ▁M ing ▁histor ies ▁on ▁the ▁life ▁of ▁the ▁em peror , ▁he ▁came ▁across ▁as ▁an ▁intro vert ed ▁half - liter ate ▁alco hol ic ▁sat ir ical ▁weak ling . ▁Given ▁this ▁dis mal ▁track ▁record ▁there ▁is ▁no ▁evidence ▁that ▁had ▁the ▁Ta ich ang ▁Emperor ' s ▁reign ▁last ed ▁any ▁longer ▁than ▁it ▁did , ▁he ▁could ▁have ▁turned ▁around ▁the ▁fort unes ▁of ▁the ▁be le ag uer ed ▁M ing ▁dynast y ▁after ▁the ▁long ▁steady ▁decl ine ▁of ▁the ▁later ▁years ▁of ▁the ▁W an li