Abstract. This study aims to see how national identity is at the Indonesia-Malaysia border. This field study was conducted in the villages of Sebunga and Temajuk in Indonesia, which are directly adjacent to the village of Telok Melano in Malaysia. In terms of language, the two communities use or at least can speak the same language, namely, Iban/Bidayuh Malay. It turns out that the different functions as an identity; so, they can choose to be Indonesian or Malaysian. This study strengthens the conclusion that the true state boundary is still just an imagination. An imagination controlled by language and pragmatic choice. The results show that the boundary between Indonesia and Malaysia in this region has been clearly defined. Physically, there are boundary markers and cross-border posts guarded by the Border Security Army (Pamtas). In addition, residential areas are also separated. However, in reality, in some ways, the limit is a pseudo. Keywords: Border, Language Identity, Sambas 1 Introduction The Indonesia-Malaysia boundary in the Kalimantan region and parts of Sumatra today was agreed through a London agreement 200 years ago. At that time, the Dutch, represented by… and the British, represented by… agreed on the division of their territory in the archipelago. The agreement arose because of the chaotic situation and detrimental to the interests of – especially – the Netherlands, in the economic activities of trade in the region. Through the agreement, it was agreed to divide the colonies on the land of Borneo. Northern Borneo, which today is part of Sarawak and Sabah (Malaysia) and Brunei, was under British rule; while the southern part of Borneo, which today is the territory of West Kalimantan, ICON LATERALS 2022, November 05-06, Malang, Indonesia Copyright © 2023 EAI DOI 10.4108/eai.5-11-2022.2329491 Choose as Indonesian but Act as Malaysian: Overview of National Identity and Linguistics of Indonesia-Malaysia Border Communities Fatmahwati A 1 , Syamsurizal 2 , Wahyu Damayanti 3 , Martina 4 , Tri Amanat 5 , Elmansyah 6 , Yusriadi 7 {syam015@brin.go.id 1 , fatm004@brin.go.id 2 , wahy057@brin.go.id 3 , mart013@brin.go.id 4 , 3amanat@gmail.com 5 , elmans@iainptk.ac.id 6 , yusriadi.ebong@gmail.com 7 } Badan Riset dan Inovasi Nasional 1, 2, 3, 4, 5 , Institut Agama Islam Negeri Pontianak 6,7