How do we know that it is the year 2023 even though there was a period in history where there were no records (the Dark Ages)?

 The year 2023 is determined by the Gregorian calendar, which is the calendar widely used in most countries today. 

The Gregorian calendar was introduced in 1582 as a reform of the Julian calendar and has been widely adopted, replacing local calendars and providing a standardized way of keeping track of time. 

Records of the calendar, such as historical documents, astronomical observations, and official decrees, have allowed us to determine the current year, even in the absence of records from some periods of history like the Dark Ages.