What are some good strategies against land takeovers in Alexandros?
Disclaimer: I have never played Alexandros, but have read the rules and examined the board.

Try to be the player in second place during the early and mid-game. This is known as the bicycle race strategy. Occupy small to medium value provinces. Spend turns collecting cards to position yourself to occupy a high value province while appearing to just be coasting. To keep the leader from getting too much of a lead, break up his provinces with Alexander.

Let another player grab a province from the leader first. With any luck, they'll use their excess cards fighting trading land grabs. Then us all those cards you've been accumulating to grab a big province and levy taxes.