They decided to settle in this city and build up over the long term.
Tips
history
From the Yuan play 《两军师隔江斗智》: Zhou Yu is reported as having '安营扎寨' at Chaisang Ford, a deliberate military move. The idiom cemented as stock language for Romance-of-the-Three-Kingdoms-style war narratives.
usage
Originally strictly military. Modern extension covers any deliberate setting-up of a long-term base — companies entering a market, migrants settling in a new city, researchers starting fieldwork.