Complex sentence: As with most of the early Bohemian rulers, Bořivoj is a shadowy figure and exact dates and facts for his reign can never be considered as completely reliable, although several major fortifications and religious foundations are said to have dated from this time.
Split into simpler sentences: As with most of the early Bohemian rulers, Bořivoj is a shadowy figure; exact dates for his reign and vital statistics cannot be established. Nonetheless, several major fortifications and religious foundations are said to have dated from this time.