Why is it hard to create a timeline of events chronicling eatths history?

Why did stalin want to spread communism? What is the history of the word awesome? What does the word chivalry mean and how was it important to a knight? Who built the aqueduct of Segovia? What century is 1814? Was polyphony used in the Middle Ages? Who was the King of France during the 1600s? Why did English people go on crusade? What is the Eurocentrism is defined as? In what centuries was humanism prevalent in Europe? What did the pilgrims use to start fire in 1620? Did the medieval people have hygiene? Who did the crusaders fight against? Why did early Chinese civilization develop free of many outside influence? What do the Romans call the sun? How was land divided on the manors? What did northern European rules do to incourage the speed of renaissance ideas? What were the views on marriage in 1600s in England? How did mining affect western settlement during the late 1800's? Because the Roman Empire was so large it was necessary to have what to lessen confusion?

Why is it hard to create a timeline of events chronicling eatths history?