A bit of back-story...

Originally, the World History Timeline started as a personal project centred around the Roman Empire - specifically the Emperors and the order and length of their reigns. So I thought creating a timeline would be a good way to visualise this - all I needed was a list of the emperors which I could then translate to my timeline.

Over time, I started to add to the timeline by including other events in Roman history such as when provinces were added to the Republic and the Empire, the names and dates of wars, who were the consuls in a particular year etc.

Of course all of this is included, not only in the primary sources (Pliny, Plutarch, Tacitus, Suetonius etc.), but also in literally 1,000s of very well-researched secondary sources. I like reading both the primary and secondary sources but, for my purposes, I wasn't after the detail, I only wanted a summary of this information in the form of a timeline that would act as a quick visual guide, so that when I was reading the source material, I also had the timeline I could refer to.

So, to build my Timeline, I only needed a summary of Roman history in the form of annals or lists of names, dates and events that I could transfer to the timeline. The obvious choice was Wikipedia.

Because I just wanted the raw data without opinions or commentary, and importantly, because this sort of information is not controversial and for which there is wide scholarly consensus, I wasn't concerned about the usual types of objections one might have to using Wikipedia as a source of historical information.

Fast forward a number of years and many thousands of entries later, this is the same approach I've used for sourcing most entries in the Timeline - records of events without commentary and opinions and for which there is general consensus.

I've continued to use Wikipedia and a number of other similar sources to create the entries in the World History Timeline. I also made the Timeline editable so that if anyone identifies any historical inaccuracies, they can update their own copy of the Timeline - and hopefully let me know so I can make the correction too.