The word "Lahijan" is originated from the economic stance the city had have during its historical periods. "Lahijan" is formed by two words: Lah, means silk and "Jan or Gan" means a place where something is done. Therefore, by compounding these two parts, the word "Lahijan or lahigan" will be made, which means "a place to obtain silk fiber".
Professor Bahram Farah'vashi who is an Iranian expert in ancient languages says in the Middle Persian Language; Lah refers to silk, and of course in Decisive Argument; Lah means the red silk. Therefore, Lahygan (today, Lahijan) is an area where silk is obtained
In Gilan there are three major Iranian language groups, namely Gilaki, Rudbari, and Taleshi, and pockets of two other groups, Tati and Kurdish. The non-Iranian languages include Azeri Turkish and some speakers of Gypsy (Romany, of Indic origin).
Gilaki is spoken by possibly three million people as a first or second language, and has had a budding literature and fledgling prose publications, including newspapers.
The five Iranian languages in Gilan belong to the Northwestern branch of Iranian. Gilaki, which has two main dialect types, eastern and western, with the Safid-rud River as the general border, is a member of the Caspian subgroup. Tati and Taleshi (Talyshi) together make up the larger dialect chains which together make up the larger Tatic family (not to be confused with Tat-Persian spoken in pockets north of the Baku area).
Among these, the two Tati pockets in Gilan, Kalasi and Kabataʾī, have their closest relatives in Upper Tarom in Zanjan province. Taleshi is a dialect chain of three main types, southern, central, and northern; and southern Taleshi is closer in type and mutual comprehension to some forms of Tati than it is to central or northern Taleshi. Rudbari may originally have been a subgroup of Tatic that has largely adapted structurally to Gilaki.
There are many subdialects of Gilaki, and, progressing to the east, it gradually blends into Mazandarani (Tabarestan). The intermediate dialects of the area between Tonokabon and Kalardasht serve as a transition between Gilaki and Mazandarani. The differences in forms and vocabulary lead to a low mutual intelligibility with either Gilaki or Mazandarani, and so these dialects should probably be considered a third separate language group of the Caspian area.
Since the time depth between southwestern Iranian and northwestern Iranian is greater than that of, for example, English and Swedish within the Germanic languages, Gilaki and Persian differ on almost all grammar points. Time depth within western Iranian, however, is not an absolute measure of distance, since northwestern Iranian and south¬western Iranian have coexisted within the same cultural zone for millennia, during which Persian has consistently been by far culturally dominant. All Caspian languages contain many lexical items (e.g., dan- “to know,” xast “to want,” guft- “to say,” tanest “can”) and certain grammatical features (the loss of the conjugation of transitive verbs and the use of ra) that most likely show quite early influence of Persian.
More recently, however, due to both the economic importance of the Caspian and the Gilān’s proximity to Tehran, Gilaki has been under¬going a massive, indelible Persian imprint: heavy influx of vocabulary (e.g., Pers. pəsər, duxtər, damad, negah kudən have replaced the native rey, kor, zama, fəndərəstən), significant syntactic interference (e.g., eżāfa), changes in vowel pronunciation, and even morpheme borrowings. One thus gets the erroneous impression that Gilaki is merely a dialect of Persian. Yet it is a mixed language, and is becoming even more mixed. Virtual one-to-one correspondences between Gilaki and Persian are commonplace, and often unavoidable: Gil. məšγul-ə taayi kudən durust kudə́n-əšåm-u γəzå bid and Pers. mašḡūl e tahīya kardan dorost kardan e šām o ḡaḏā būdand “they were busy providing and making dinner
Lahijan enjoys a climate known as "moderate Caspian”. This weather pattern emerged from the influence of the currents of both the Alborz Mountain slopes and the Caspian Sea. But before knowing about this weather pattern, we should discuss the model of climate system and of course Gilan's spacial geo system.
Gilan includes the northwestern end of the Alborz chain and the western part of the Caspian lowlands of Persia. The mountainous belt is cut through by the deep transversal valley of the Sefid-Rud between Manjil and Eemamzadeh Hashem near Rasht, the capital of Gilan Province. To the northwest, the Talesh highlands stretch a continuous watershed separating Gilan and Azerbaijan.
Except at their northern end, where the Heyran pass at the top of the Āstārāčāy valley does not exceed 1600 m, they are over 2,000 metres (6,600 ft) high, with three spots over 3,000 metres (9,800 ft) including the Baqrow Daḡ, the Ajam Daḡ, and the Shah Moʿallem or Masouleh Daḡ. Their eastern and northeastern side is deeply carved by parallel streams flowing down towards the Caspian, resulting in a comb-shaped pattern. The western Alborz itself, to the east of the Safid-rud valley, is wider and more intricate, with three parallel (WNW-ESE) ranges; the southernmost and lowest one is represented in Gilan by the Asman-sara Kuh in the Ammarlu district; the medium one is the most continuous, from the Kuh-e-Dalfak to the Keram Kuh, whereas the transversal valley of Polrud clearly divides the northern range into Kuh-e-Natesh and Kuh-e-Somam or Somamus, the highest spot of Gilan. All these mountains have a very complicated geological structure and tectonic history which connects them to the structural complex of central Persia.
Though all those mountains cover a greater area than the plains, these are the most specific feature of the province, and locally, the word Gilan often refers to the plain areas or particularly to the central plain.
This large parallelogram of lowlands is heterogeneous and can be divided into two main parts: the delta of the Safid-rud in the east and the Fumanat plain in the west. The former has been entirely built by the Safid-rud, a river with a high discharge and a high alluvial content. The higher part is made out of coarse ancient alluvial material, whereas in the lower part, north of Astaneh-e Ashrafiyyeh, the river often changed its course through thin silty and clayey material; it has thus abandoned its former northeastward course, which flowed into the sea at the prominent angle of the plain near Dastak, and presently flows northwards and builds a smaller living delta jutting out into the Caspian between Zibakenar and Bandar kiashahr.
The Fumanat plain to the west intermingles marine alluvial deposits and former sandy beach-lines with abundant alluvial deposits from the numerous rivers draining the southern part of Talesh highlands. They do not reach directly the sea, but converge into the lagoon of Anzali with a single outlet to the Caspian through the dune-covered sandy coastline. The lagoon is constantly getting smaller and shallower under the effect of silting. On the contrary, the streams of northern Talesh and eastern Gilan, even the more abundant Polrud, do not bring alluvium enough to counterbalance the action of a coastal current going eastward, and thus could not build more than a narrow ribbon of lowlands, only a few kilometers wide between Astara and Safid-rud and to the east of Qasemabad, and some 10 km wide at the mouth of the Polrud around kelachay..”.
