This region includes not only Spain and Portugal, but also the Pyrenees and the area south of the Massif Central. It includes the three important shrines of Santiago de Compostela, Guadalupe, and Montserrat, together with the roads leading to them.
In the E Pyrenees, the itineraries dealt with here are to/from Montserrat. The main route is, as expected, over the Perthus pass and Barcelona, the main road from Roman to modern times. Estienne's version of this is significantly different, but I do not know the reason for this. Less expected are the routes used by Nompar de Caumont, who went over the Cerdagne on the way out and via Andorra on the return. If you'd asked me before I started on this project whether pilgrims went via Andorra, I would have thought that very amusing, but here we have one who did just that.
The two itineraries that went south to Seville did not use the road now known as the Via de la Plata, but went via Guadalupe, Purchas from Santiago via Lisbon, and the Bruges Itineraries south from Ponferrada.
As this site deals primarily with itineraries from the north, it's not surprising that by far the most used route to Santiago is the one across N Spain now known as the Camino Francés. There are some variations - Künig von Vach, for example, recommends lower-level routes to bypass both Rabanal and O Cebreiro - but this remains much the same from the Codex Calixtinus in the 12th century to Villuga in the 16th. The greatest variations are at the Pyrenean end. The most-used route was over Roncesvalles, but later itineraries used the road via Irun and the tunnel of St Adrian; Estienne describes this and does not mention Roncesvalles, and in the post-medieval period this became the main crossing in the W Pyrenees. Künig von Vach seems to have used the Baztan valley route between Pamplona and Bayonne, and Purchas went from Bayonne to St Jean Pied de Port, presumably via the Nive valley. The Codex Calixtinus claims that people coming from Toulouse and further east used the Somport pass, but this is not borne out by the itineraries dealt with here. All of them went via Ostabat/St Palais and Roncesvalles, a much shorter route with a lower pass. The Codex route north of the Pyrenees is in any case very vague, so I have not plotted it here.
Other roads to Santiago mentioned are from Corunna (now called the Camino Inglés), the road to Finisterre, and the road via Oviedo which the Bruges Itineraries describes.
Villuga lists other routes to both Guadalupe and Montserrat, but I have not plotted these as yet.