The writing time of the three poems in "Sixteen Character Order" is titled "1934 to 1935". Briefly talk about this period of time

This period of time is the time for the long march of one army.

They set out from Jiangxi and passed through the Nanling Mountains, Yunnan-Guizhou Plateau, Hengduan Mountains and Qinling Mountains to the Loess Plateau.

Central Red Army (First Red Army): 1934.10.16-1935.10.19. Starting from southern Jiangxi and finally arriving at Wuqi Town in northern Shaanxi. The departure date is based on Yudu, the largest troop gathering and departure point. Ruijin's troops set off on the 10th, and the Ninth Army Corps began to move east of Changting on September 30th.

Central Red Army: 86,859 people at the time of departure (including a small number of government agency personnel in the central column and thousands of civilians temporarily summoned to carry supplies. 19,880 people in the 1st Army, 17,805 people in the 3rd Army, 12,168 people in the 5th Army , 10,922 people in the 8th Army, 11,538 people in the 9th Army, 4,693 people in the Military Commission Column, and 9,853 people in the Central Column). Before crossing the Xiangjiang River, there were nearly 70,000 people. After breaking through the Xiangjiang River, the number was reduced by half. After crossing the Jinsha River, the number was 24,000. After crossing Jiajin Mountain (arrived at Xiaojin) had 18,000 people, and after crossing the grassland, it was estimated to be 14,000 people (of which 5,000 people from the Ninth Army Corps and others were incorporated into the Fourth Front Army). When they arrived in northern Shaanxi, there were about 7,000 people from the 1st and 3rd Army Corps, the Military Commission Column, and the Central Government Agency.