It is Mappila Muslims who are the native Muslims and are majority in Muvattupuzha/Kothamangalam and northwards. They are connected to Perumbavoor-Aluva-Kodungallur belt than to south. Marriages are not really common between Mappila and Thulukkar (also called "Annan"). In Muvattupuzha, there are also Muslims from Mahi called "Mayyakkar" who are the local community leaders of the Mappila Muslims. Muvattupuzha market area has many Muslims who came from Malabar (Mappila Khalasi ancestors).Almost all or a huge majority of Muslims in Travancore region are Thulukkars (Tamil Muslims) - from sub-castes of Rawther, Labba, Marakkar, etc. This includes Muslims of TVM, Kollam, Pathanamthitta, Alappuzha, Kottayam, Idukki and Ernakulam districts. They are district of Mappila Muslims in Malabar, who are mainly concentrated in 6 Malabar Districts, Chavakkad Taluk, Coorg, and Mangalore.
Some hubs of Travancore Muslims in Travancore (not necesarily they are majority, but have a good chunk of population) - Beemapally (TVM), Nedumangad, Varkala, Kollam, Karunagapally, Kayamkulam, Alappuzha, Kollakadavu (near Chengannur and Mavelikara), Mannar, Pathanamthitta Petta, Kattoor Petta (near Kozhencherry and Ranni), Vaipur (near Mallapally), Kadakkad (near Pandalam), Erattupetta, Thodupuzha, Muvattupuzha, Aluva, Kizhakkambalam, etc.
In Pathanamthitta district, Muslims are very less (less than 5%) and it is the district having least percentage of Muslims. Still Muslims have their own hubs in Pathanamthitta district - like Pathanamthitta Petta and Kulashekharapathy (both in Municipality), Kattoor Petta, Naranganam Petta, Vaipur, Angadi Petta (in Ranni), Kadakkad, etc. One important thing to notice is, Muslims hubs in Pathanamthitta is known as Petta. Probably Erattupetta also got that name like this.
But now very few Travancore Muslims speak Tamil. They are integrated with Malayali society, and majority of them are in Business or Gulf.
Rawther Hanafi Muslims are lesser in Ernakulam district including Muvattupuzha-Kothamangalam. They, may be some 20-25% of the Muslims in Muvattupuzha taluk. Apart from Muvattupuzha pettah, hanafi Muslims are present in some small pockets only in Ernakulam district..like Pattimattom (not Kizhakkambalam), Nellikkuzhi, Thottumukham, Kakkanad Athani, Ernakulam city, Aroor-Nettoor-Chandiroor regions etc. In Muvattupuzha, Hanafis are concentrated in the Pettah and Kizhakkekkara areas. While, Muslims are present in rural and village areas also in Kodungallur-N.Parur-Aluva-Perumbavoor-Muvattupuzha-Kothamangalam region unlike southern districts and Ernakulam city area, where Muslims are concentrated around ghettoes or particular region.
I think only in Karunagappilly, Kayamkulam, Trivandrum in south Kerala where Mappila Muslims are significant. Thazhathangadi, Kottayam also. Rest, I guess may be Hanafi Muslims only.