What is the significance of girding belts?
Rashi: Kasdim dress this way.
Radak: They were beautiful in the eyes of Yehudah; Bnei Eretz Yisrael did not gird their loins with belts. In Bavel, a meal begins from when he unties his belt, but not in Eretz Yisrael, for they did not wear belts there (Shabbos 9b) 1 . According to the opinion that Tefilas Ma'ariv is optional, if a Ben Bavel untied his belt [to eat before praying Ma'ariv, we do not exert him to gird and pray before eating.
Malbim: In Bavel they gird tightly, like it says in Shabbos (9b. Refer to 23:15:1:2*.)
The Gemara said that Bnei Bavel and Bnei Eretz Yisrael differ about this; it did not say which wear belts. R. Chananel says that some explain that only Bnei Eretz Yisrael wear belts. How will he explain our verse? The other Meforshim there imply that both wear belts, just only in Bavel they gird tightly. When one girds his belt, he blesses Ozer Yisrael bi'Gevurah (Brachos 60b). It does not teach about one who does not wear a belt! However, it also says to bless 'Oter Yisrael b'Sif'arah' when donning a turban, and did not teach about girls who do not wear turbans! (PF)
What are "Seruchei Tevulim"?
Rashi: The excesses of big hats. We do not find anything like Tevulim in Tanach. It is understood from context 1 . Also Yonason translates 'hats that rest.'
Rashi citing Menachem: Tevulim is [colored,] like "va'Yitbelu Es ha'Kutones ba'Dam" (Bereishis 37:31). Seruchei is like "v'Serach ha'Odef" (Shemos 26:12) (what sticks out from) the colored turban. Radak ? it refers to Seruchei Tzenifim Tevulim; the word Tzenifim (turbans) is omitted, like "k'Eder ha'Ketzuvos" (Shir ha'Shirim 4:2; it should say 'k'Eder Rechelim ha'Ketzuvos'), "u'Ma'achalo Beri'ah" (Chabakuk 1:16; Seh is omitted) and similar verses. These turbans have excess that hangs down in back. This is not the custom of Bnei Eretz Yisrael. Seruchei applies to the Kasdim due to their Tzenifim, just like "k'Elah Noveles Aleha" (Yeshayah 1:30) ? the tree is called Noveles due to its leaves. The same applies to "Megulechei Zakan u'Keru'ei Begadim" (Yirmeyah 41:5) and similar verses.
Malbim: They are long hats.
Since it is on the head, it is a hat. It says "va'Yitbelu"! Perhaps he means that we do not find an adjective Tevulim. (PF)
What is "Mar'e Shalishim"?
Radak: This is like "v'Shalishim Al Kulo" (Shemos 14:7). They appear great and dignified in their dress and manners.
Malbim: They appear mighty.
Why does it say "Demus Bnei Bavel Kasdim Eretz Moladtam"?
Radak: Bnei Bavel are Kasdim. Their custom is the custom is their birthplace; they did not take it from another land, the way Yisrael desire [Bavel's] customs are prefer them to Yisrael's own customs.
Malbim: This is the appearance only of Bnei Bavel whose birthplace is [Eretz] Kasdim. Foreigners in Bavel did not dress like this.
