And after that he gave [unto them] judges about the space of four hundred and fifty years, until Samuel the prophet.
Note 5 at Ac 13:20: Some scholars have mistakenly said that this 450 years included the 400 years in Egypt, the 40 years in the wilderness, and about 10 years of the rule of judges. However, Ac 13:18-19 clearly states that it was after the 40 years in the wilderness and the division of the Promised Land to the Israelites that this 450-year period began.
Also, by adding up all the years of oppression and the years of freedom mentioned in the book of Judges (from Jdg 3:8 to Jdg 16:31), we find a total of 409 years that would be considered under the rule of judges. In 1Sa 4:18, Eli was also spoken of as judging Israel for 40 years. That would bring the total time of the judges to 449 years, or so close to the time period Paul mentions here that there could be no doubt he is referring to the time after the death of Joshua (Jdg 2:8) to the death of Eli (1Sa 4:18).