Generally a player will want to start or continue an expedition. This is represented by playing a numbered card on his side of the board, next to the map of the same color.

Remember that number cards must be played in ascending order. Since this player has placed the "4" in the row, it's too late to play the "3" if he gets it later! This adds a great amount of tension during the game.

Notice the handshake card at the top of the row? That's an investment card that will affect scoring at the end of the game.