Although these cultures are rooted in a similar island lifestyle, the shift in culture for the East Timorese came with the arrival of the Portuguese in the 1500s when Catholicism was introduced and accepted by the majority of the people (an event that took place over a couple hundred years). While this only slightly altered the way of life for the people, it placed a huge wedge between the Catholics and the Muslims, who were also living on Timor.
Despite the religious differences, the people of Timor Island, no matter their faith, primarily continued to live off the land and sea into the 1970s, when differences were magnified and political tensions began. Indonesia invaded and took control over the entire island in this decade, leading to greater independence movements and a sharpening divide between the Catholics and Muslims. This strong rule by the Indonesian government magnified the people's religious differences, but also placed emphasis on numerous other differences, such as the numerous aspects of Portuguese culture the East Timorese had adopted.
The political debates also led to a slowly changing methodology of identifying for the people of Timor-Leste. The many similarities between the people took second priority as the people on both sides focused on differences as the East Timorese began identifying first with the differences and only secondly by their commonalities.
Although Timor-Leste is now independent, little has changed in the culture or society in recent years as the people remain fairly rural and identity is still strongly based on their Catholic faith and traits that make them unique from the Indonesians. Their differences with neighbors have also continued, but are now expanding to include arguments with Australia over maritime borders, leaving Timor-Leste few allies and growing isolationism, which is oddly helping secure cultural traditions that have been lost on many neighboring islands.