The Swazian is a poorly defined geological stage in South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

 extending from about 4,000,000,000 years ago to 3,000,000,000 years ago http://www.stratigraphy.org/bak/geowhen/region_South_Africa.html, encompassing some of the Hadean and much of the Archean on the Geologic time scale

Geologic time scale

The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...

. Other scales http://www.palaeos.com/Timescale/Precambrian.htm assign the Swazian to parts of the Paleoarchean

Paleoarchean

The Paleoarchean is a geologic era within the Archaean. It spans the period of time 3600 Ma to 3200 Ma —the period being defined chronometrically and not referenced to a specific level in a rock section on Earth. The oldest ascertained life form is from this period....

 and Mesoarchean

Mesoarchean

The Mesoarchean is a geologic era within the Archean, spanning 3200 Ma to 2800 Ma . The period is defined chronometrically and is not referenced to a specific level in a rock section on Earth. Fossils from Australia show that stromatolites have lived on Earth since the Mesoarchean. The Pongola...

, 3.5 to 2.8 billion years ago. The Swazian is not recognized by the International Commission on Stratigraphy

International Commission on Stratigraphy

The International Commission on Stratigraphy , sometimes referred to by the unofficial "International Stratigraphic Commission" is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, geological, and geochronological matters on a global...

 nor by the Geological Society of America

Geological Society of America

The Geological Society of America is a nonprofit organization dedicated to the advancement of the geosciences. The society was founded in New York in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hitchcock, John R. Proctor and Edward Orton and has been headquartered at 3300 Penrose...

, the two most widely accepted developers of international geologic time scales.