God established Abraham as a ruler in Canaan, the land over which his mother's people ruled. The northern and southern boundaries of Abraham's territory were marked by the settlements of his two wives. Sarah dwelt in Hebron and Keturah dwelt in Beer-sheba to the south. Abraham's wives bore him 7 sons. Daughters were born also, though they are not named in the Bible. Abraham's sons married these daughters and the daughters of Na-hor, Abraham's older brother.
Sons were born to Abraham by concubine servants as well. Ishmael, was born of Hagar and, according to the Septuagint, Eliezar of Damascus was born of Masek. In the New Jerusalem Bible (following the Vulgate) Abraham says to the Lord: "Since you have given me no offspring... a member of my household will be my heir." The Septuagint offers this: "What will you give me, seeing I go childless and the heir of my house is Eliezer of Damascus, the son of Masek, my domestic maidservant." Eliezar as a son of Abraham by a maidservant, parallels the story of Hagar. This means that Abraham had 9 sons: Ishmael, Eliezer, Isaac, Joktan, Zimram, Medan, Midian, Ishbak and Shuah. There were also daughters. Clearly, God fulfilled His sovereign will concerning Abraham that he should be the "Father of a multitude".
Hagar and Masek are to Abraham's household what the concubines Zilpah and Bilhah are to Jacob's household. They built up the ruling houses of these patriarchs by producing many offspring. If the biblical pattern is to be trusted, we may reasonably suspect that Hagar and Masek were the servants of Sarah and Keturah, just as Zilpah was the servant of Leah and Bilhah the servant of Rachel (Gen. 30). That Masek was Keturah's servant is supported by the fact that the name Masek is still found among the south Arabian Mahra. They dwell in Yemen, Oman and southern Saudi Arabia (see map). This is where we would expect to find the descendents of Abaham by Keturah's servant Masek.
Some Mahra/Masek are semi-nomadic and others are settled in small semi-fortified villages where they farm and raise chickens for eggs and goats for milk. They are known to aggressively defend their territories and water sources and are regarded as belonging to the warrior caste. Their chiefs control the goods and persons who pass through their lands.
The Mahra/Masek are an endogamous tribe, which means that they exclusively marry within their kinship circle. Most men have only one wife, but the chief may have more than one. Children receive inheritances patrilineally, with the first-born son receiving the lion's share. Young girls are valued for childbearing and for the bonding of families through marriage. This was especially true in Abraham's time for both wives and concubines.