《隋书·列传·卷十六》
于是调发榆林北部的百姓，一直到其牙地，又东到蓟地，长三千里，宽百步，全国百姓都来割草开御道。
乃发榆林北境，至于其牙，又东达于蓟，长三千里，广百步，举国就役而开御道。
So he dispatched the people of northern Yulin, all the way to his Yadi, and then to the east of Jidi, which was 3,000 miles long and 100 miles wide. The people of the whole country came to cut grass and open up the imperial road.