Complex sentence: His successes in Italy secured Nikephoros a friendly welcome and honours on his return to Constantinople, but he is not mentioned again for several years, until the outbreak of war with Bulgaria in 894.
Split into simpler sentences: His successes in Italy secured Nikephoros a friendly welcome and honours on his return to Constantinople, but he is not mentioned again for several years. Little is known of his activities between his return from Italy and until the outbreak of war with Bulgaria in 894.