20 Avos S.A.R. Coinage, Macao's Return to China

The 1999 date places this piece squarely at the handover of Macau from Portugal to the People's Republic of China on December 20th of that year — the last European colonial transfer in Asia. The Monetary Authority of Macao retained issuing authority through the transition, and the pataca remained in circulation unchanged, a deliberate signal of continuity under the "one country, two systems" framework negotiated between Lisbon and Beijing in the 1987 Joint Declaration.

Portugal had administered Macau since the mid-16th century, making it the longest-running European presence in Asia by a considerable margin.