In recent meanderings through my family history, we have found a link to medieval (15th and 16th century) Spain (Pamplona region to be precise) - so, is it possible to access records (births, deaths and marriages) from that region, from that time?
Pamplona is in the region of Navarra and so you will need to search for records from this region. Family Search has quite a lot from this time period and is regularly adding more.
Spanish records, in my experience, are normally very good with more information than you find in some other countries. You also need to be aware of naming conventions, the child of a marriage will take the mothers maiden name as their second surname so if Fred Smith and Emma Jones have a child it would be called Jane Smith Jones or Jane Jones Smith. Jones in the childs' case is not her middle name it is her second surname. This helps in tracking the maternal line back through the generations (this naming is common to male and female descendants).