1. border regions or frontier areas between two countries or territories, especially those that are disputed or contested
Usage: plural form; often used in historical or political contexts
2. areas of low-lying land, typically marshy or swampy, along a border or coast
Usage: less common; geographical sense

Examples

• The marchlands between the two kingdoms were heavily fortified.
• Soldiers patrolled the marchlands to prevent unauthorized crossings.
• The marchlands have long been a source of conflict and negotiation.
• Local people in the marchlands developed a unique culture blending both nations.
• Trade routes through the marchlands connected distant regions.
• The disputed marchlands remained under international scrutiny.