Minecraft command block teleporting command

First of all I know that /tp (playername) 1 2 3 will teleport the player to the coordinates 1 2 3. (I also know about @a @ p and @r. But that's not what i'm asking for. Let me explain what I'm asking for with an example. I want to teleport everyone BETWEEN coordinates 1 2 3 and 4 5 6 to coordinates 7 8 9. I know that /tp @a[1 2 3] 4 5 6 will teleport everyone in the coordinates 1 2 3 to 4 5 6 but only if they're on 1 2 3. So what command can I use so only players in a certain area will be teleported?