Notice it mentions the families of the north, and then it states that Babylon will come against "this land" and "all the nations round about". So we have the north mentioned, Judah mentioned ("this land"), and "all the nations round about.". If there is still any doubt in your mind, Jeremiah was kind enough to start explicitly listing the nations included in this prophecy starting in verse 18. Again, there are many (plural) nations involved in the seventy years, they are explicitly listed starting in verse 18, and "these nations" will serve the king of Babylon seventy years. It's seventy years of servitude of many nations. Not seventy years of desolation. Please read the scriptures and respect context and grammar.
The prophecy has a lesser but a parallel fulfillment regarding other nations, but the direct fulfillment regarding the desolation of Jerusalem is clearly indicated in related scriptures;
In the first year of Da·ri′us the son of A·has·u·e′rus of the seed of the Medes, who had been made king over the kingdom of the Chal·de′ans; in the first year of his reigning I myself, Daniel, discerned by the books the number of the years concerning which the word of Jehovah had occurred to Jeremiah the prophet, for fulfilling the devastations of Jerusalem, [namely,] seventy years. Daniel 9:1-2
The charter of Cyrus the Great synchronizes with Daniel 9:1-2 so there should be little question in the minds of those that have confidence in the Bible as the unerring, inspired Word of God, and are sincerely interested in knowing the truth of this matter from a Biblical perspective.