The whole difficulty about this text will become evident when we compare it with a different translation. In King James Version, for instance, we read: "And when he had destroyed seven nations in the land of Chanaan, he divided their land to them by lot. And after that he gave [unto them] judges about the space of four hundred and fifty years, until Samuel the prophet". So we have two versions of events: according to the first the conquest and division of the land Canaan lasted 450 years (GNB); the other ascribes the said number of years to the period of the judges (KJV). Contradiction is obvious.
One could say at this point that Good News Bible should be adopted because it is newer than King James Version and supported by more recent findings and research on the Biblical text. The issue is not so simple, though. It is true that older Bible versions tend to present Acts 13:19,20 in the sense that King James Version does, whereas newer ones tend to align with Good News Bible, but it can by no means be treated as a rule, which is well exampled by the Aramaic Bible in Plain English, published in 2010. Faultiness of this argument does not mean, however, that there is no argument at all. And the best one is provided by the Bible itself in contextual verses.
First of all, it must be said that the 450 years cannot refer to the conquest and division of the land. All these events took place during Joshua's life: "So Joshua took the whole land, according to all that the LORD said to Moses, and Joshua gave it for an inheritance to Israel according to their divisions by their tribes" (Josh. 10:42, 11:23 WB). Joshua lived to be 110 years old (Josh. 24:29). Therefore, if Joshua died at the age of 110, conquest and division of the land could not have lasted 450 years.
Apparently, this was a period much shorter than 450 years. One year, one month and five days after Exodus Israel went out of the Sinai desert and turned towards the wilderness of Paran (Num. 33:3, 10:11-13). Then, from Kadesh-Barnea spies were sent into Canaan (Num. 13:3-26; 32:8-13). At the division of the land (Josh. 10:42; 11:23) Caleb, one of the spies, spoke out: "Forty years old [was] I when Moses the servant of the LORD sent me from Kadesh-Barnea to explore the land ... And now, behold, the LORD hath kept me alive, as he said, these forty and five years, even since the LORD spoke this word to Moses, while [the children of] Israel wandered in the wilderness: and now, lo, I [am] this day eighty five years old" (Josh. 14:7,10 WB).
Thus, 45 years elapsed between the spying of the land and its division. In the meantime Israel spent 40 years in the wilderness because of their lack of faith in God's promise. It was precisely after the spies came back that the 40-year period began (Num. 14:22,23,33,34; Acts 7:36; Heb. 3:9). So the conquest of the land must have taken 5 years. For the same reason the period from Exodus to the division of the land lasted a little more than 46 years (a little more than a year from Exodus to sending spies from Kadesh-Barnea + 40 years in the wilderness + 5 years of the conquest of the land).
Could the 450 years mentioned in Acts 13:19,20 refer to the period of the judges? Even though the book of the Judges does not mention the length of the period explicitly, it does mention lenghts of particular sub-periods. All these numbers stated in Judg. 3:8-16:31 sum up to 410 years. Additionally, 1 Sam. 4:18 mentions the last of the judges, Eli, who "had been a leader in Israel for 40 years" (GNB). So finally we arrive at the number of 450 years:
|Israel conquered by king of Mesopotamia (Judg. 3:8)||8 years|
|Othniel's reign (Judg. 3:11)||40 years|
|Israel conquered by king of Moab (Judg. 3:14)||18 years|
|Ehud's reign (Judg. 3:15,30)||80 years|
|Iarael conquered by Jabin (Judg. 4:2,3)||20 years|
|Deborah's reign (Judg. 4:4, 5:31)||40 years|
|Midian captivity (Judg. 6:1)||7 years|
|Gideon's reign (Judg. 8:28)||40 years|
|Abimelech's reign (Judg. 9:22)||3 years|
|Tola's reign (Judg. 10:1,2)||23 years|
|Jair's reign (Judg. 10:3)||22 years|
|Ammonite captivity (Judg. 10:8)||18 years|
|Jephthah's reign (Judg. 12:7)||6 years|
|Ibzan's reign (Judg. 12:8,9)||7 years|
|Elon's reign (Judg. 12:11)||10 years|
|Abdon's reign (Judg. 12:13,14)||8 years|
|Philistine captivity (Judg. 13:1)||40 years|
|Samson's reign (Judg. 15:20, 16:31)||20 years|
|Eli's reign (1 Sam. 4:18)||40 years|
Obviously, the period of 450 years mentioned in Acts 13:19,20 refers to the period of the judges, not the period of the conquest and division of the land.