The Lu family's ancestral temple was in Luoyang, so it was known as the sub-capital of Datang.
Chang'an was 800 miles away from Luoyang. Normally, it was only a day's ride from Chang'an to Luoyang, but there were many people traveling from Chang'an to Luoyang, so it would take at least three days.
Luckily, there were a lot of posthouses along the way, so it didn't matter if they moved slowly.
Many officials and nobles sent servants to Luoyang in advance to clean their houses in Luoyang.
Although the Emperor went to Luoyang, there would still be some people left behind to guard Chang'an. After all, Chang'an was closer to those barbarian tribes.
Prince Su and Prince Rong stayed in Chang'an, temporarily taking charge of the military power of Chang'an.
Chang'an had been the capital of Datang for a long time.