勢力

1. Origins, structure, and basic meaning

• Structure: 勢力 (せいりょく) is a noun for a power bloc or the influence exercised by a group.
• Basic usage: 二つの勢力が対立する refers to opposing groups; 勢力を伸ばす describes a company expanding its influence.

2. Common pitfalls and similar expressions

• Power group and extent of influence
  • The first context names the powers themselves, while the second treats influence as something that can be extended.