evidence: Every year, on 1 July, Hong Kong marks the day where it was returned from British to Chinese control. [...] Hong Kong had developed a vastly different political and economic system from mainland China, which since 1949 had been under authoritarian one-party Communist rule. [...] China agreed to govern Hong Kong under the principle of "one country, two systems", where the city would enjoy "a high degree of autonomy, except in foreign and defence affairs" for the next 50 years.