As- samiri a individual

Samiri is derived from smr. They say smr i.e he nailed it, i.e he made it fast firm or strong with a nail or nails, a being called smr. Hence samri is on who makes things fast with nails, i.e one belonging to the profession of black-smiths, carpenters, etc. this samariat means, a people who carry on the profession of blacksmiths, carpenters, etc. i.e. artisans. The mischief-maker, seems to belong to this class. So samiri may be a descriptive or attributive name. or it may be a relative noun from (the Samaritans) a people said to be one of the tribes of the children of Israel; or a sect of the Jews, differing from them in many of their institutions. Properly speaking they were inhabitants of Samaria. The name is now restricted to a small tribe of people living in Nublus and calling themselves "bene Yisrael". Their history as a distinct community began with the taking of Samaria by the Assyrians in 722 B.C.  (Lane and Jew Encyclopaedia)

The Encyclopaedia Judaica (under "Samaritans") summarizes both past and present views on the Samaritans' origins. It says:

Until the middle of the 20th century it was customary to believe that the Samaritans originated from a mixture of the people living in Samaria and other peoples at the time of the conquest of Samaria by Assyria (722–721 BCE). The biblical account in II Kings 17 had long been the decisive source for the formulation of historical accounts of Samaritan origins. Reconsideration of this passage, however, has led to more attention being paid to the Chronicles of the Samaritans themselves. With the publication of Chronicle II (Sefer ha-Yamim), the fullest Samaritan version of their own history became available: the chronicles, and a variety of non-Samaritan materials. According to the former, the Samaritans are the direct descendants of the Joseph tribes, Ephraim and Manasseh, and until the 17th century CE they possessed a high priesthood descending directly from Aaron through Eleazar and Phinehas. They claim to have continuously occupied their ancient territory and to have been at peace with other Israelite tribes until the time when Eli disrupted the Northern cult by moving from Shechem to Shiloh and attracting some northern Israelites to his new followers there. For the Samaritans, this was the "schism" par excellence.

—"Samaritans" in Encyclopaedia Judaica, 1972, Volume 14, col. 727.

Furthermore, to this day the Samaritans claim descent from the tribe of Joseph:

The laymen also possess their traditional claims. They are all of the tribe of Joseph, except those of the tribe of Benjamin, but this traditional branch of people, which, the Chronicles assert, was established at Gaza in earlier days, seems to have disappeared. There exists an aristocratic feeling amongst the different families in this community, and some are very proud over their pedigree and the great men it had produced.

—J. A. Montgomery, The Samaritans, the Earliest Jewish Sect: Their History, Theology and Literature, 1907, p. 32

How do the Samaritans portray themselves during the period of Assyrian rule? According to their Chronicles, the righteous remnants who belonged to "the community of the Samaritan Israelites, that is the tribe of Ephraim and the tribe of Manasseh, sons of Joseph, and a few other priests and a small number from the rest of the tribes of Israel" who "did not deviate from the way of the holy law, nor did they worship other gods. They did not behave as the nations did, and did not forsake the chosen place Mount Gerizim Bethel, but they continued to worship the Lord their God..."

J. Macdonald, The Samaritan Chronicle No. II (Or Sepher Ha-Yamim) From Joshua To Nebuchadnezzar, 1969, op. cit., II Kings - II Chronicles, H, H*-J*, p. 178.

“Samiri’s name as generally believed, was Musa Ibn Zafar. Ibn Jarar has narrated from Sayiddina Ibn ‘Abbas {ra} that Samiri was born in the year when under the orders of Pharaoh all male Israili children were to be killed. His mother, fearing the worst, put him in the hallow of a cave and covered its mouth.” – Tafsir Maa’riful Qur’aan, page 144.

Sayiddina Ibn ‘Abbas {ra} says that he belonged to a nation of cow-worshippers who somehow reached Egypt and pretended to join the religion of Bani ‘Israil whereas in actual fact he was a hypocrite. (Qurtubi) – Tafsir Maa’riful Qur’aan, page 143.

Where did they come from, if they were not from around Egypt?

“According to Sayddina Sa’id ibn Jubair {ra} he was a Persian from the Kirman province.” – Tafsir Maa’riful Qur’aan, page 143.

SAMARITANS OR SAMARIANS?

As mentioned earlier, the traditional view of the origins of Samaritans is based on II Kings 17. The verse in question is II Kings 17:29 where the Hebrew word shomronim or shomeronim 

 appears and is usually translated into English as "Samaritans" (underlined in the Hebrew text below).

But every nation still made gods of its own, and put them in the shrines of the high places which the Samaritans had made, every nation in the cities which they dwelt... (RSV)

The name shomronim that appears in II Kings 17:29 is associated with the worship of idols. However, the Samaritans do not address themselves by this name at all. They call themselves shamerin 

, that is "keepers" or "observers" of the Torah.[13] The Samaritans themselves make a clear distinction between their own ancestors and the inhabitants of Samaria. For example, in the part of the Samaritan Chronicle II which corresponds to I Kings 16 of the Hebrew Bible, the biblical account of the founding of Samaria by Omri is followed by a note which explains that the inhabitants of Samaria and its nearby cities were called "Shomronim after the name Shomron".[14] Thus the distinction between the people of Samaria and the Samaritans is clearly maintained in the Samaritan Chronicle II. Put simply, shomronim means the "inhabitants of Samaria" and it has nothing to do with shamerin, "keepers" or "observers" of the Torah, which the Samaritans use for themselves. In fact, a long line of Samaritan scholarship has already pointed out this fact, which, unfortunately, is ignored by those at their own peril. For example, about 100 years ago James Montgomery pointed out that the Samaritans:

.... call themselves by the ancient geographical apellative, Samerim, which they interpret however as meaning "the Observers", i.e., of the Law.[15]

Similarly, The Interpreter's Dictionary Of The Bible confirms that:

... the Samaritans prefer to style themselves 'Shamerim' 

 i.e., "the observant" - rather than 'Shomeronim' 

 i.e., "the inhabitants of Samaria."[16]

The Encyclopaedia Judaica under the entry "Samaritans" says:

Little guidance is obtained from the name of the Samaritans. The Bible uses the name Shomronimonce, in II Kings 17:29, but this probably means Samarians rather than Samaritans. The Samaritans themselves do not use the name at all; they have long called themselves Shamerin; i.e., "keepers" or "observers" of the truth = al ha-amet, both the short and long forms being in constant use in their chronicles. They take the name Shomronim to mean inhabitants of the town of Samaria built by Omri (cf. I Kings 16:24), where the probable origin of the word Shomronim is to be found).[17]

[13] J. A. Montgomery, The Samaritans The Earliest Jewish Sect: Their History, Theology And Literature, 1907, The Bohlen Lectures For 1906, The John C. Wilson Co.: Philadelphia, p. 24.

[14] J. Macdonald, The Samaritan Chronicle No. II (Or Sepher Ha-Yamim) From Joshua To Nebuchadnezzar, 1969, Beihefte Zur Zeitschrift Für Die Alttestamentliche Wissenschaft - Volume 107, Walter de Gruyter & Co.: Berlin, I Kings XII-XXII, I, C*, p. 163.

[15] J. A. Montgomery, The Samaritans The Earliest Jewish Sect: Their History, Theology And Literature, 1907, op. cit., p. 24.

[16] "Samaritans" in G. A. Buttrick (Ed.), The Interpreter's Dictionary Of The Bible, Volume 4, 1962 (1996 Print), Abingdon Press, Nashville, p. 191.

[17] "Samaritans" in Encyclopaedia Judaica, 1972, Volume 14, Encyclopaedia Judaica Jerusalem, col. 728.