Fun fact about dices (at least in Scandinavia) is that they are quite easy to date in archaeological contexts. Up until the 13th century, the numbers were arranged differently. 1 was opposite of 2, 3 of 4 and 5 of 6. From the 14th century onwards they are arranged so all opposite sides turns out 7 with addition (1 is opposite of 6, 2 of 5 and 3 of 4).