Osculating eccentricities and inclinations of the trans-Neptunian region after 4.5 Gyr of integration. Neptune undergoes disc migration from 39 to 21 au (top plot) and 27 au (bottom plot) and then it reaches its current semimajor axis at about 30 au following Eq. (1). Rows containing three plots highlight the separate coloured components. There are some differences, mainly concerning the 3:2, 4:3, and 5:4 resonances; they are less populated if Neptune’s migration is as deep as 21 au.