"V'Eleh" implies that it is connected to what came above. What is the connection?
Malbim: The previous verse mentioned three things - conquering the land, dividing it, and serenity in the land. Our Perek discusses conquering, Perakim 12 and 13 discuss division, and Perek 14 ends with "the land was quiet from war." What Moshe conquered and divided is mentioned along with that of Yehoshua.
When did Yisrael defeat these kings and take their land?
Rashi: It was in the days of Moshe.
Whose land was from Nachal Armon until Har Chermon?
Malbim: This included the land of Sichon and Og. The following verses detail which part belonged to which.