Final answer:
Charlemagne's empire extended from northern Spain to Bohemia and marked the first time Western Europe was united since the Roman Empire. His rule was characterized by continuous military campaigns and a lack of robust bureaucratic structures, culminating in his coronation as Emperor of the Romans in 800.
Step-by-step explanation:
Charlemagne's empire at its height extended from northern Spain to Bohemia, which is in the present-day Czech Republic, stretching across a vast region of Western and Central Europe. During his rule from 768 to 814, Charlemagne led numerous military campaigns to expand his domain, marking the first unification of Western Europe since the fall of Roman authority. His major areas of conquest were in Central Europe, which formed the earliest groundwork for 'Germany' as a state. However, the empire did not have robust governmental structures such as a standing army or official currency, and Charlemagne spent much of his reign issuing decrees and leading wars to maintain control over his territories. On Christmas Day in the year 800, he was crowned Emperor of the Romans by Pope Leo III, which demonstrated a deep alliance between the Frankish throne and the church while also creating a precedent for later conflicts and relationships between empires and the papacy.