In his book “The Conservative nature of the British rule of Sri Lanka”  (Vijitha Yapa 2014), Dr. Wickremeratne says that even conversion to  Catholicism under the Portuguese or the Dutch Reformed Church under the  Dutch did not alter the culture, values, thought and social structure of  the Sinhalese and the Tamils.

• European rule was marked by continuity rather than change, says Dr.Upali C.Wickremeratne

The Portuguese, Dutch and British rulers  thought it prudent to maintain the traditional Sinhalese and Tamil  social and economic structures so that their rule was accepted by the  population 
Dr.Upali C.Wickremeratne.

There would otherwise only be a very remote possibility of finding out  everything that was happening and of which it was also important to be  aware 
Ryckloff van Goens

Sri Lanka was under European rule partly or fully from 1505 to 1948. And yet, its traditional social structures remained more or less the same during this period. According to UK-based historian, Dr.Upali C.Wickremeratne, this was due to the fact that the Portuguese, Dutch and British rulers thought it prudent to maintain the traditional Sinhalese and Tamil social and economic structures so that their rule was accepted by the population.

In his book “The Conservative nature of the British rule of Sri Lanka” (Vijitha Yapa 2014), Dr. Wickremeratne says that even conversion to Catholicism under the Portuguese or the Dutch Reformed Church under the Dutch did not alter the culture, values, thought and social structure of the Sinhalese and the Tamils. The Muslims retained their culture and beliefs despite persecution by the Portuguese and the Dutch.  
The author points out that tolerance and accommodation of traditional differences had been an aspect of the Sri Lankan mindset from ancient times. Its European rulers endorsed it and gave effect to it.  
When the kings ruled Sri Lanka, the separate identities of various castes, religious and linguistic groups were strictly maintained. There was no forced Sinhalization of the Tamils or forced Tamilization of the Sinhalese in areas in which they ruled. These communities lived separately just as the various castes lived in separate areas within a village.

Communal conflict

“There is no evidence of communal conflict. Cultural separation seems to have been permitted,” Dr.Wickremeratne says.
Caste, with its hierarchical structure based on notions of the high and the low, purity and pollution, was endemic in Sri Lanka from the earliest times. Caste strictures were strictly enforced and these related to social mixing, marriage and dress. “Caste is an integral part of Sinhalese and Tamil societies. It has survived for over a thousand years. There is no evidence of inter-caste conflict in pre-European Sri Lanka,” the historian avers.
Communities that came from outside Sri Lanka like the Karawa, Salagama and Durawa and settled down along the Western and Southern coasts around 1250 AD, were accommodated and allowed to live but as separate communities, Dr.Wickremeratne says. However, over time, these communities were Sinhalised.    
The Sinhalese and Tamil kings saw to it that caste norms were observed. For example, ministers and administrative officials, including village headmen, were drawn from the Goigama caste in the case of the Sinhalese and from the Vellala caste in the case of the Tamils. 
Though Buddhism did not sanction caste, in practice, the caste system was upheld by the Buddhist priesthood. The priests themselves were drawn from the Goigama caste.
According to Dr.Wickremeratne, there is no evidence of the low castes rejecting their caste out of frustration. It is possible that the low castes attributed their inferior status to their misdeeds in previous lives (as per the law of karma), he says and adds there were no instances of castes revolting against their status.    
Sinhalese and Tamil castes were generally associated with particular economic activities but this was not strictly adhered to. For example, most castes drew their sustenance from agriculture though agriculture was identified with the Goigamas or the Vellalas. 

Social and economic structure 

When the Europeans ruled parts of the island first and expanded their rule to cover the entire island later, they adopted the existing social and economic structure wholesale. They continued the practice of appointing only the Goigama as village headmen in the Sinhala areas and Vellalas in the Tamil areas. 
When the Dutch appointed a non-Vellala to the post of “Majoraal” in Jaffna, there was such commotion and uproar that the appointment had to be cancelled and never be repeated.
The Dutch strove to make the Sinhalese and Tamil castes perform their traditional functions and also make them pay their traditional dues to the rulers (ie: to them, as they were the rulers). John Gidon Loten and Thomas Van Rhee noted the obligations of the various castes in copious detail. The Dutch were alarmed when some persons of a caste meant to do manual work took to soldiering because the latter job was less strenuous. This was strictly disallowed.  
The Dutch also created new work for some castes. The Salagamas were given a monopoly on cinnamon peeling. As cinnamon was an important item of trade for the Dutch, they were granted special privileges. They were exempted from duties and tolls, and had the right to indulge in coastal trade without paying duties. Salagama headmen were free from the overlordship of the Goigama village headman. The Salagamas were placed under a Dutch official. The headmen of the Karawa and Durawa castes were also made independent of the Goigama village headmen.

Wickremeratne also notes that the Dutch created new caste occupations. Thomas Van Rhee’s list mentions shoemakers, painters, carpenters, copperware makers, and cabinet makers as separate castes. It is likely that they were members of existing castes who were separated and made to perform the tasks required by the Dutch. 
Sri Lanka’s traditional headman system was maintained and strengthened by the Portuguese and the Dutch. It was through the traditional headmen that they ruled. The Sinhalese headmen, who were mainly Goigamas, were in charge of cultivation of commercial crops, collection of taxes, securing services for the government such as Divel and Uliyam, compilation of Thombos (land records), enforcement of religious laws, adjudication of disputes and the suppression of rebellions.

Vital information 

Above all, the Dutch and the Portuguese, relied on the headmen for vital information about local conditions. Dutch Governor Baron van Imhoff wrote: “These chiefs are the channels through which the population is to be ruled and their power if of necessity very great.”
When advising his successor to keep some of the Sinhalese chiefs physically near the residences of Dutch officials, Ryckloff van Goens wrote: “There would otherwise only be a very remote possibility of finding out everything that was happening and of which it was also important to be aware.”
The headman was key to putting down rebellions. When Jan Schreuder faced a rebellion in the Galle and Matara Koreles, he threatened to dismiss the headmen in charge if they did not put down the revolt. And within a short time the rebellion was crushed.
The headmen were graded. The Mahamudaliyars and the Mudaliyars of the Governor’s Gate were the Governor’s advisors. Mudaliyars of the Attepattu were attached to each of the Disavas. The Korale Mudaliyars were attached to the Korales, the principal subdivision of the Disavani. The Lascarins, who were the soldiers were commanded by Muhandirams. Their subordinates were Arratcies.
The Mudaliyars were paid by “Accommodessans” which were government lands which varied in size. 
At one stage, the question of making the post of Mudaliyar hereditary arose. But the Dutch decided to keep it non-hereditary so that all those qualified had a fair chance of getting the post.

Religious Conversions

The Portuguese and the Dutch were ardent proselytizers. But both failed to achieve much as they found that while many converted in deference to authority and the use or the threat of use of force, most practiced Buddhism or Hinduism secretly. 
The Roman Catholic converts were more steadfast about their new religion than those who converted to the Dutch Reformed Church as the practices of the Catholic church matched practices in Buddhism and Hinduism.
The Dutch made conversion compulsory for office holders like headman and teachers in schools. Marriages could be registered only upon conversion. But it did not take the Dutch long to discover that conversions had little impact on the beliefs and practices of the converts which were traditional. 
On the whole, the Dutch tolerated the Buddhists and Hindus, but were very harsh on the Muslims, especially Muslims from India, as these were seen as business rivals. Indian Muslims could not settle down in Dutch held territories. Only Muslims from Bengal were welcomed as they brought rice to Sri Lanka.