River System: The Periyar, the Chalakudy, the Karuvannur, and the Ponnani (Bharatha Puzha) are the main river systems in the district. They take their origin from the mountains on the east, and flow westward and discharge into the Arabian Sea. There are a number of tributaries also joining these main rivers. Climate
The Nairs who till recently followed the Marumakkathayam family system constitute the most important section among the Hindus of Thrissur. Now a vast majority of them have taken to agriculture while others have been absorbed in Government service and other professions. Till a few decades ago, the Nairs were divided into several sub-castes and inter-dining and inter-marriages were not permitted among them. The Nairs attached to Namboodiri and Kshatriya houses for certain domestic and religious services were called Illathu Nairs and Swarupattil Nairs respectively. Charna Nairs, Pallichans, Vattekadans, Odathu Nairs, Auduru Nairs and Attikurussi Nairs are other Nair subdivisions. Every Nair had a title affixed to his name. Achan, Kartha, Kaimal and Mannadiar were some of the titles of nobility conferred on the Nairs by the Rajas of Cochin while Panikkar and Kurup were the titles of those who maintained Kalaries as their hereditary profession. Menon was the title conferred on the Nairs who followed a literacy career. When the country underwent tremendous changes, strict observations of caste rules fell into disuse.
The Samanthans, though very few in number in the district, are said to have sprung from the union of Kshatriya men with Nair women. They have marumakkathayis. The Ezhavas who follow Makkathayam are numerically one of the strongest communities in Thrissur. They have attained important positions as merchants, landowners and cultivators. A good number of them have also taken to learned professions. Velythedans, Velakkattalavans and Chaliyans are hereditary washermen, barbers and weavers respectively. Ezhuthachans otherwise known as Kadupottans who follow the patriarchal system of inheritance are supposed to be the descendants of Pattar Brahmins. They are hereditary village school masters. The Valans, Arayans and Mukkuvas are fishermen mostly living in the coastal areas of Thrissur district. Besides, there are a number of other castes like the Mannans, Velans, Pulluvans and Pattilans in the district.
Another section among the Hindus is the Kammalas who are divided into carpenters, masons, braziers, blacksmiths, goldsmiths etc. As their service is essential, they are till engaged in their traditional occupations. But in recent years a sizable section of them have taken to modern education and steady progress. The Devanga Chettis and Kaikolans are weaving castes found in Mukundapuram taluk. They immigrated into the district from Mysore and Coimbatore respectively. The Vaniyans Kudumis, Pandithans, Kallans, Pandarams, Ambattans, Vannans, Chakkiliyans and Kusavan are also immigrant castes. The Vaniyans wear the sacred thread and resemble Konkani Brahmins. The Pandarams are engaged in making Pappadam, the favourite crisp cake of the Malayalees. Ambattans are Tamil barbers and Vannans are Tamil washermen.
The Scheduled Castes and Scheduled Tribes form a significant section among the Hindus of the district. The former are mainly agricultural labourers and are found in all the Taluks. The Scheduled Tribes of the district are the Kadar, the Malayar and the Mathuvans. The Kadar of the area belong to two clans, the Anamala Kadar living at Parambikulam and West Kadar living at Adirappilli. The Malayar and Kadar are nomadic people.
Christians form the second largest community in the district. It is strange that Cranganore where the Gospel of Christ is believed to have been first preached in India should have the lowest proportion of Christians among the taluks of the district. The earliest Church in the district was a Nestorian branch of the Asiatic Church presided over by Bishops usually ordained in Persia. The early Christians were known as Syrian Christians. The Syrians Catholics, Latin Catholics, Jacobites, the Reformed Syrians and Protestants are some of the main sections of the Christian Community in the district . In Thrissur and its neighbourhood there is a small community of Christians known as Chaldeans.
The Christians have a predominant place in the social and economic life of the district. Trade and agriculture are the chief occupations of the community. There have been several survivals of Hindu customs among the Christians such as caste prejudice, belief in astrology, omens, witchcraft and charms, the tying of the tali as part of the marriage ceremony and its removal on the death of the husband, the performance of Sradha or the annual ceremony for the soul of the dead etc.
Fasting is a significant form of religious observance. It is observed on Shashti, Ekadasi, Pradosham, Full Moon and New Moon days. On Shashti viz. the sixth day of the fortnight, fast is observed by those who wish for issue. Ekadasi is sacred to Vishnu and Pradosham to Siva. Fast in honour of the Goddess Parvathi is observed on Full Moon days. The observance of festivals is an important aspect of religious activities. Here special mention may be made of the three major festivals of the Malayalees viz. Onam, Vishu and Tiruvathira. Among the ceremonies still current may be mentioned Namakaranam, Chorunu, Vidyarambham, Upanayanam and Sradha.
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