The Sui Dynasty of China reigned for less than fifty years in the sixth and seventh centuries CE. Nonetheless, the Sui Dynasty is considered especially important in Chinese history. The Sui united the northern and southern Chinese kingdoms and returned the rule of China to the hands of the ethnic Han Chinese. They also constructed the Grand Canal, which facilitated the movement of people and goods around China for several centuries.

The correct answer is democratic. The Roman Republic did allow voting but voting rights were unequal and didn't conform to representative democratic principles. Upper class citizens could unite and veto majority decisions on the basis of class.

The Greeks were known for the extent of the participation of the people in political life. Greece is widely known as the birthplace of democracy for this very reason. Greek women, however, had essentially no political power. Rigid hierarchies were not distinctive about Greece, as all civilizations experienced social stratification. Some leaders of Greece were benevolent, but it was not a significant enough consistency to be a distinctive feature of Greek civilization.

The Roman Republic featured a senate, representative government, and rule of law. The definition of a republic is a political system in which people elect their officials, which can be seen in this answer choice, but not in any of the others. The Mandate of Heaven and civil service exams were common of the Chinese government. Tyrants would not be leaders in a representative republic. Lastly, the Roman Republic did not see a separation of church and state. Conversely, the two were tied together very officially when Constantine made Christianity the official religion of the empire in the year 312 CE.

When he named himself dictator for life Julius Caesar did something unprecedented in Roman history. Previously (with the notable exception of Sulla) dictators were chosen by the elected officials of the Roman Republic to serve for a six-month or one-year term. The actions of Julius Caesar contributed to the downfall of the Roman Republic and the rise of the Roman Empire.

Sparta's dual-kingship system ensured that there was always a king in the city while also enabling one king to command military operations outside Sparta. The most notable example of this is Leonidas' presence (and subsequent death) at the Battle of Thermopylae did not sent Sparta into disarray, as his co-ruler Cleomenes still reined. In this way, both military and civil life in Sparta continued to run smoothly.

The Twelve Tables were the earliest known attempt at establishing a legal system in Ancient Rome in the fifth century BCE.

Pericles, the city's dictator, ruled Athens at the height of the city's military and cultural influence. Both a great statesman and soldier, he is considered one of the most important figures in ancient history. Unfortunately, he was carried off by plague in 429 BC and the city was never the same.

As far back as the Han dynasty, China demonstrated an elaborate bureaucracy. Entry to this bureaucracy was dependent on the results of civil service exams for all eligible contenders. 

After the fall of Rome, European political structures changed from an imperial model, in which a sovereign had both legal and real authority over military and economic policies, to a feudal system, in which aristocrats pledged their allegiance to a king, and were expected to provide men-at-arms and taxes.

Communism is a political ideology within the Marxist school of thought, which did not begin until the 19th century.

There were few, if any, democratic Republics during this period.

Capitalism did not begin until the end of the feudal period.

Tribalism can be found all over the world, even to this day, but the breakdown of Rome did not cause Europe to become tribal.