How many Eras are there and when will there be a new one?

the mongolian invasion of china and central asia resulted in a disruption of the silk road as the chinese garrisons lost support from the chinese kingdoms which fell under the mongols. however, as the mongols established a formal dynasty in china, the successors of genghis khan restored the garrisons along the silk road allowing the safe travel caravans again.

information is crucial for making good decisions

a sample of water is taken and kept in a beaker in a freezer at a constant temperature of 0°c. if the system is at dynamic equilibrium, which of these statements is true?  

there are many answers to this question, such as a diplomat, ambassador, soldier, united nations employee, cia, etc.