Simplify the following text for a Grade 12 native English-speaking person.
Original: While China , Japan , Korea and Vietnam had long included chopsticks as part of their traditional eating utensils , the use of chopsticks in a limited sense spread to other Asian countries in recent centuries with the influx of Chinese immigrants in Southeast Asia .
Simplified: Chopsticks are the traditional eating utensils of some countries including China , Japan , Korea , Taiwan , and Vietnam .