駐留

1. Origins, structure, and basic meaning

• Structure: 駐留 (ちゅうりゅう) means troops remaining in a foreign or specified area. 駐留していた is the state; 駐留期間 is its duration.
• Basic usage: Foreign forces are stationed on an island in a novel; museum records show how long a unit remained.

2. Common pitfalls and similar expressions

• Troops remaining in an area and recorded duration of presence
  • Location appears as 島に; duration through compound 期間. The second focuses on how long rather than merely whether troops were present.