Complex sentence: At the western edge of Europe and of Islamic expansion, the Reconquista in the Iberian Peninsula was well underway by the 11th century; it was intermittently ideological, as evidenced by the "Codex Vigilanus" compiled in 881.
Split into simpler sentences: At the western edge of Europe and of Islamic expansion, the Reconquista in the Iberian Peninsula was well underway by the 11th century. It was intermittently ideological, as evidenced by the "Codex Vigilanus" compiled in 881.