posted 04-14-2002 07:06 PM
First you must consider one very crucial fact. The south of Spain was invaded by the Moors(Arab Muslims) and they took much of the whole of Spain before being forced out again over many years in what is called the 'Reconquista'. This could present a problem to travellers from the North wanting to get to Muslim occupied Sevilla, which was held till near the very end.
You should be able to find plenty of info on the reconquista on the web or at a library.Other considerations would be temperature, geography and weather.
The centre of Spain in particular can get very hot during the summer. I was there in October, and it was very plesant weather. There is also a very severe wind which is called the 'Mistral' which blows at a certain time of year, so you will want to avoid that, but I can't remember when it blows.
Also, the centre of spain is very sparsely populated in parts. There are areas between Gijon and Seville where there are vast plains with no trees, villages or water to be seen. Today there are wheat fields, but historically it may not have been used. This could be difficult to cross, especially in summer.
As for going by ship, I don't know anything about that, except to say that Portugal did not exist for part of the Middle Ages. I think it may have come into existence only during the Reconquista.
'Medieval' covers a great span of time, so once you've researched you'll be able to pick the best time to go, such as after the reconquista, where you can expect least probelms from the weather and the Moors.
Erik