Due to every country having different climates and the Shariat of Islaam is universal in Nature. Then to state that this or that particular dress in only the Sunnat, how will a Muslim in winter in Russia dress and how will the Muslim in summer dress in Saudi Arabia. So one form of dress will be condusive for one area in one season but not good for another area in another season.
Whereas our claim is Islaam is for all time, for ever place, for all people, for all conditions, for every nook and cranny of the world. In the light of the Hadith, Nabi (S.A.W) wore a Kurta, a shawl, a hat, a turban, alungi and even a trouser when it was presented to him. For a very healthy discussion see Shaamil Tirmidhi which has the commentary of Sheikh Muhammad Zakariyya (A.R) and the booklet "Kurta, Topee, Turban" by Moulana Fazlur Rahmaan Aazimi.
Thus the Ulema has after studying the Shariat (i.e. the various Ahadith etc. formulated by some principles :
1.) Should be loose fiting, no attractive part of the body should be made out;
2.) The basic are (aura) must be covered, area between the Naval to below the knee;
3.) The garment, especially the trouser must be above the ankles;
4.) The garment should be preferably white;
5.) The garment has horizontal and vertical thread to make up the fabric, both these threads must not be red or yellow;
6.) The garment must not be made of silk for men, it can only be used under special circumstances;
7.) The garment must be purchased from Halaal earnings;
8.) It should be a mean of decorating the body, within the limits of Shariah;
9.) It should not resemble the dress of non- muslims;
10.) It should not create pride and arrogance in a person One should know that Nabi (S.A.W) wore a garment worth 2000 dinars. Whilst Imaam Maalik (A.R) used to wear new clothing daily.
11.) The muslim must avoid following the fashion of the day. Know also that the Nabi also wore green. Pride can also be caused by wearing simple, coarse clothing. The person in his heart will feel, 'look how pious I am'
12.) Men should not don the specialised dress of women, at times non-muslims wore dresses/garments which have no religious significance in their religion, then without detestment Muslims may wear such clothing.
Some times non- muslims wear a particular garment in one area as a religious feature or mark, but that very same dress in another area is not worn with that connotation, then to wear that garment in one area will be permissable and in the other area not - permissable. However, while it is possible to wear the Kurta then one should do so.As a rule , the Ulema have found that in any area, the layman should abserve the dress of the reliable, pious, righteous, practical Ulema - e- Rabbani Haqqani of that area, then imitate these Ulema. This is closest to the Sunnat. One will not expect any Aalim, to have no beard, wearing a tie, having trousers below the ankles, with no hat let alone a turban on the head projecting piety.
The Ulema who have understood the Deen will dress in such a method which will be nearest to the Sunnat.Thus to say the Kurta is not the Sunnat dress is not valid and also to state that the Kurta is only the Sunnat dress is also not correct.
