Simplify the following text for a Grade 12 native English-speaking person.
Original: The first non-Aboriginal people to visit and have sustained contact with Aboriginal people in northern Australia were the Macassans from Sulawesi and other parts of the Indonesian archipelago .
Simplified: The first non-Aboriginal people to visit and have long term contact with Aboriginal people in northern Australia were the Macassans from Sulawesi and other parts of Indonesia .