The term Kongu means honey or nectar of flowers. The Kongu country had vast stretches of forests. It was believed to be rich in honey or nectar of flowers and hence it came to be known as the Kongu. The people who lived in that part of the Tamil country were called as Kongars. The ancient Kongu country extended upto River Kaveri in Mysore.The people of this region identified themselves by either wearing garlands of distinct flowers or by having the totem of an animal or a bird. They especially wore garlands of Kongam flowers (Cochlo spermum Gossypium ).A sangam verse that praises Nannan, the Velir chief of the Coorg and Mysore region, referred him as 'Ponnam-kanni Nannan'. Since the Kongam flowers are yellow in colour, like the gold, 'Ponnam-Kanni' was described as a beautiful garland of the gold like yellow Kongum flowers. It is also mentioned in a verse of Perumkadai of Konguvel, that Barugur and North Coimbatore plateau formed the Southern extension of the Mysore plateau and had plenty of Kongam or Kongilavam trees.
 

The ancient Kongunadu comprised of the Southern Mysore region. The Kongu country had distinct physical features. After the Kongar occupied the modern Coimbatore region the Kongu country extended upto the parts of the present Kerala The upland parts of the Kongu country had general elevations of over 3000 feet. The general slope of this region was towards south-east as indicated by the course of the rivers Kaveri and Kabini. It was the rain shadow region and the climate was highly variable in character. This difference in rainfall was reflected in the vegetation. The forest region of Kongunadu belonged to the deciduous forest classification.  The only fertile and alluvial plain of the ancient Kongu was the central part of the plateau where the river Kaveri and Kabini flow. This part was called as Punnadu-the land of water. The Kongu country consisted of a mass of hills on the east between 3000 and 3700 feet high. The Anamalai hills formed the southern boundry of the Kongu country. In between the Vellimalai ranges and Anamalai ranges, a few kilometers south-west of Coimbatore lies the Palghat Gap. The Palgat Gap is of historical importance from the pre historic times. The Nilgiris is the next important hill range of Kongunadu.

The major river of the Kongu region both in the ancient and modern era is the river Kaveri. It rises in the Bagamandala near Thalai Kaveri in Coorg and flows south-eastwards across the plateau.
The Bhavani rises in the silent valley forests of the Valluvanda taluk of the Malabar district. Before it enters into the Kongu, it joins with the Siruvani, rising in the Attapadi valley of Kerala.
Amaravathi rises in the Anjanda valley of the Kerala State between the Anamalai hills and the Palani hills. It descends in a northerly direction and widens at Kallapuram, the mouth of the Ajanda valley in Udumalpet.
In the Salem district, the Toppur river which was also known as the Toppiar or the Veppadiyar, is one of the minor tributaries of the river Kaveri.
The Sarabhanga-nadi is another tributary of the Kaveri river. This is formed by the union of two streams, namely the Omalur East river and the Omalur West river.
 

The Geology of the Kongu country is very interesting. While in the Coimbatore district, all the rocks belong to the great gneissic series, iin the Salem and Dharmapuri district, rocks belong to granite, syenite, charnockite, foliated granitic gnesis, amphibolite, ultramatic rocks- Bluish grey to dark grey coarse grained rock of the Northern Kongu.
 

This  Iron furnace tells us that Kongu was rich in Iron ore deposite

The mineral wealth of the Kongu country is noteworthy.   Iron oredeposits were extensive, though of low grade. The deposits were found in the districts of Chitteri, Rasipuram, Namakkal and Valliampatti areas. Further, from the Sangam verses, we can conclude that Kongu was rich in Gold deposits. It is also to be noted that two-thirds of the Roman coins were obtained from Coimbatore and it's surroundings. This substantiates the belief that Kongu country was a bone of contention of the three great Tamil monarchs as well as the other great ruling powers of the South India.

The climate of the Kongu country was generally more pleasant than that of the adjoining parts of Tamilnadu. The year was divided into four main seasons; the dry season from January to March, the hot season from April to May, the Monsoon season from October to December, and the pleasant months were January and February. Because of the interior location of the Kongu country, it was not directly affected by the tropical cyclonic storms and depressions of the Bay of Bengal. Kongu country occassionally received heavy downpours particularly in the parts of Coimbatore, Nilgiris, Talaimalai and the Anamalai hills.