This study aims to fill a gap in the history of Islamic Extension in the Umayyad era and try to shed light on the life of Maslama bin Abde Malek bin Marwan, the Arabic prince and the Arabic militant who spent his life in striving to save the northern and the northern eastern boarders of the Umayyad country and stabilizing it. This role is giving to him since the days of his father Abdul AlMalik bin Marwan and during his brothers' caliphate Al-Waleed and Sulaiman , his cousin Omar bin Abdul AlAziz and his brothers Yazid and Hisham. We find a few modern and old historians who study the life of this Umayyad militant despite of his leadership role to destroy some of the revolutions which threatened the stability in the Umayyad State. And those who get the narration of Maslama news are few and different in views, especially his conquests in the northern and northern eastern boarders for the Umayyad State. In order to reach the historical facts which is imposed by the subject nature of this study by collecting Maslama's news from the first hand resources and understanding and analyzing them in a subjective and methodic way. Try to link between these narrations and comparing them to reach to fact about the historical event, giving clear details regarding the role of Maslama's conquests to this sensitive front of the Umayyad State. The researcher follows the historical methodic based on analyzing and criticizing to reach the wanted conclusions to clarify the big role of a Muslim Leader Who was neglected in the Islamic history. The study is divided into an introduction, preface ,the conclusion and three chapters. The first chapter talks about Maslama's bin Abdul Almalek bin Marwan biography regarding his kinship and birth, breeding and growing up, his nickname, surnames and his epithet, his sons and wives and his relations with the persons of the Umayyad's house beginning with his father the Caliphate Abdul AlMalik bin Marwan passing his brothers the Caliphates Al-Waleed, Sulaiman, Yazeed and Hisham sons of Abdul Almalek, and his special relation with his cousin the Caliphate Omar bin Abdul Alaziz , ending with his relations with many of the Umayyad State Leaderships military and administratively, in the end of the chapter we talk about his death and the Elegies which is said to him. The second chapter concentrates on the role of Maslama bin Abdul Almalik in protecting the interior security for the Umayyad State. It concludes two main points : in the first the researcher discusses the administrative roles for Maslama bin Abdul Almalik, which is divided into four administrative stages during different historical periods. The second talks about Maslama's role to overcome some interior revolutions in the Umayyad State, he returns the stability to the State; these revelations are the revelations of Shothab AlKarejey and Yazid bin Al Mohalb bin Abi Sofra wbich were in the Iraq. The third chapter talks about the military role of Maslama bin Abdul Almalik in stability of the northern and northern east boarders for the Umayyad State. This role is divided into five different stages beginning with the last days of his father Abdul Almalik bin Marwan caliphate until the era of Hisham bin Abdul Almalik bin Marwan. The researcher states in the end of the research some conclusions, which we ensures that every stage of the military stages which is led by Maslama either in Rome States or in Armenia and Atherbegan is a history by itself, it should be studied alone. His role is important as other conquests like Qutaiba bin Muslim Al-Bahely and Oqba bin Nafee and others. The embargo of Constantpole holds a big rank not only for the military history of the Umayyad State, but also for the Islamic extension in Europe. The study comes to a conclusion which is mentioned by few historians who talks about Maslama which is state that the life of this Umayyad conquest is embodying the morals of an Arabic horseman and a noble prince who is appreciated by others, and clarify even shortly the most important aspects of his social and political life with his family or with people. Despite his high rank to his family and nation he doesn't care to come to the throne even though his army is about 40,000 included the best Umayyad princes, but the one who follows his character finds that he sees the caliphate is not suitable for him, but his father raises him on fighting and courage, and the conquest is better than sitting on a temporary throne that he deserved to be the Caliph more than any of his half brothers for his noble career and good reputation speaks for itself.