Thai society in the early 20th century. Ni Kuang changed the name of the character to Cheng Chao-an, after Chao'an county in eastern China, the home of Cheng Chi-Yong's ancestors. He also developed the idea of Cheng being sent by his mother to live and work with fellow Chinese migrants in Thailand, after his father had been killed in a fight. She gave her son a jade necklace symbolising peace, protection and good fortune, as a reminder to avoid trouble. It was not unusual in Hong Kong cinema for the director to amend the script during filming, and The Big Boss was no exception. When Lo Wei replaced the original director in late July 1971, he was unhappy with the script and re-wrote it, without Bruce's knowledge. Lo later recalled, "I wouldn't tell him I was re-writing the script for fear of affecting his morale. In my hotel room, he would often discuss the script with me which would leave me tongue-tied, so I would tell him I needed to rest, and as soon as he left I would be burning the midnight oil in order to get the script ready for the next day's filming." Filming Bruce Lee flew from Los Angeles to Bangkok via Hong Kong on 12 July 1971. Raymond Chow, concerned about renewed interest from Shaw Brothers, had wanted him to fly directly to Bangkok, but Bruce refused, stopping in Hong Kong briefly to greet a friend and make a few phone calls. Bruce stayed in Bangkok for five nights, and it was here that he met most of the cast and crew and also Raymond Chow for the first time. Filming commenced on 22 July in Pak Chong, a small town situated some 90 miles (150 km) northeast of Bangkok, on the northern edge of the Khao Yai National Park, Thailand's oldest reserve; it also serves as the gateway to the northeast (Isan) of Thailand from the Bangkok Metropolitan Region. Pak Chong would be Bruce's home for about four weeks, and he made no secret of his dislike for it in letters to wife Linda, describing it as a lawless, impoverished and undeveloped village. Due to the lack of fresh food, Bruce was losing weight due to a lack of proper diet, having to eat canned meat and supplement his diet with vitamins, which he had thankfully brought along. He occasionally lost his voice through