section_path: Other types/Other variants
section_name: Other variants
paragraph_text: Other variants
  
  The early Roman calendar, created during the reign of Romulus, lumped the 61 days of the winter period them together as simply "winter." Over time, this period became January and February; through further changes over time (including the creation of the Julian calendar) this calendar became the modern Gregorian calendar, introduced in the 1570s.