There was the possibility of an alliance between Timur and the European realm against Muslim powers in the early 15th century, much as the attempts towards a Franco-Mongol alliance a century before, especially since the Ottomans were already threatening Constantinople at that time.
There was the possibility of an alliance between Timur and the European states, against the Ottoman Turks that were attacking Europe. These mirrored attempts towards a Franco-Mongol alliance a century before, especially since Ottoman offensives were already threatening Constantinople at that time.