Ohalos, Chapter 18, Mishnah 10. This is the closing mishnah of the entire masechta, and it continues a pattern that runs through these final mishnayos: a steady search for taharah. After chapters upon chapters of tumas meis and of ohalim that carry that tumah, the Mishnah now finishes by listing the places where the tumah does not reach.
The subject here is mador ovdei kochavim, the dwelling place of non-Jews. Chazal decreed such a dwelling tomei out of a concern that a nefel, a stillborn child, may have been buried there and never removed. Our Mishnah teaches that there are ten kinds of places to which this decree was never extended.
The Mishnah's opening words give the count: "Asarah mekomos", ten places, and concerning them it states "ein bahen mishum mador ovdei kochavim", that no tumah attaches to them on account of a non-Jewish dwelling. The Mishnah then goes through them one at a time.
One: Oholei Arviyim
"Oholei arviyim", the tents of Arabs, who would travel from place to place and never settle down in one spot. Two explanations are offered. According to one approach, they in fact did not bury their nefalim in such a tent, precisely because they knew they would soon be moving on; only when they settled somewhere would they bury there. According to a second approach, it would simply have been unworkable to include them in the decree: since these people are constantly on the move, every place they passed through would become tomei, and Chazal recognized that such a decree could not be sustained.
Two: Sukkos
"V'hasukos", temporary huts. The Bartenura explains that these were used by the workers out in the field, in particular by those stationed there to watch over the produce.
Three: Tzrifin
"V'hatzrifin". A tzrif is a shelter in which a person would occasionally spend the night. Its defining feature is that it has no roof at all: two walls are simply leaned one against the other to form a point at the top. This word appears in Seder Moed as well, in the first perek of Maseches Sukkah, in the case of one who makes his sukkah k'min tzrif. There is no roof there, only two leaning walls, and Rebbi Eliezer holds that such a sukkah is pasul, because a sukkah requires a roof, and here there is no visible distinction between wall and roof. So beyond being an invalid sukkah even when built of kosher s'chach, this structure earns its place as the third item on our list of places where one need not be concerned for tumah.
Four: Burganin
"V'haburganin", storage sheds out in the field. The Bartenura writes l'hachnis bo peiros mipnei hageshamim: their purpose was to bring the produce inside and shield it from the rains.
Five: Alketoyos
"V'ha'alketoyos". Picture a canopy held aloft by four posts, no different in form from a chuppah. During the hot months people would sit underneath it to escape the heat, since the air moved in freely from all sides. The Bartenura links the term to botei hakayitz, houses used in the summer, and note that in Aramaic kayitz is rendered kayta.
Six: Beis Sha'ar
"U'beis hasha'ar", a gatehouse. Sha'ar means an entranceway, and bayis here refers to the small booth stationed at the entrance to a courtyard, what we would call a security hut. There is no concern of tumah there.
Seven: Avir Shel Chatzer
"V'ha'avir shel chatzer", the open, uncovered area of a courtyard.
Eight: Merchatz
"V'hamerchatz", a bathhouse. Here too there is no concern of tumah.
Nine: Mekom Hachitzim
"U'mekom hachitzim", the place where weaponry was kept in storage. Chitzim are arrows.
Ten: Mekom Halegyonos
"U'mekom halegyonos", the place where the king's forces would take up residence, that is, a military encampment. The word legyon refers to an army.
The Common Thread
What unites all ten is their temporary character. In a place of that sort it is not reasonable to assume that anyone buried a nefel, and therefore such places were never folded into the gezeirah of mador ovdei kochavim. This holds even where someone happened to remain there longer than forty days: Chazal still did not extend their decree of tumah to such a location.
Reviewing the List
Maseches Ohalos thus finishes with a roster of ten locations exempt from mador akum, that is, from the rabbinic tumah rooted in the suspicion that nefalim lie buried beneath a dwelling, and in every case the reason is that the residence there is only for a short while. The list runs as follows: the tents of the nomadic Arabs, who never settle in one spot; huts; the tzrif, whose pair of walls lean one upon the other with nothing at all serving as a roof; the burgan, into which a field's produce is stored away from the rain; the alketoyos, that four-posted canopy under which one sits for a bit of air in the summer; the beis sha'ar, the small booth at the entranceway where a watchman is generally posted; the uncovered space of a courtyard; the bathhouse; the depot where the arrows were held for times of war; and mekom halegyonos, the encampment of the chayalei hamelech, the king's soldiers.
Ending in Taharah
The Tosfos Yom Tov cites here, in the name of Rav Moshe Tenner zecher tzaddik livrachah, a beautiful observation. Just as Maseches Keilim opens with tumah and concludes with taharah, so too Ohalos: it begins with tumas meis and with the ohalim that convey it, and it goes out in taharah, closing with the ohalim that remain tahor. And there is a remez in the eighteen perakim of the masechta: chai hu yoducha.
Of course, a masechta never truly ends; we only hope to return and review it again. Hadran alach Maseches Ohalos.