One such information is the History of Tamils and it’s Great Emperors,who not only expanded their kingdoms till Himalayas but also extended their Empire to overseas, like Cambodia,Vietnam.. Tamil Kings,Imayavaramban Neduncheralaathan, Karikal Chozhan and Ariyappadaikadantha Kadandhanedunchezhian , Rajendra Chola have reached Himalayas, conquering Kingdoms all the way.

During the course of his North Indian Expedition, Karikal chola, reached Himalayas,after conquering Kingdoms on the way,and Planted Chola flag in Himalayas.

Not only that,he created a Mountain Pass/ passed through a Himalayan Pass.This is recorded in Tamil Literature Silappadhikaram and Periya Puranam.While Silappadhikaram dates back to the period of Sangam Literature,Periya Puranam, a Religious Work that deals with the Lives Shiva Devotees, belongs to middle ages.

He went along the Chola Mandala Karai (Coromandel Coast) defeating kings whoever opposes him on his way , went along crossing Kalinga and Vajra Desam with Kosambi as its capital that was in bengal area and reached Himalayas.

ChoLa Pass and ChoLa Mountain Range :

Cho La is a summit pass located 5,420 metres (17,782 ft) above sea level in the Solukhumbu District in northeastern Nepal. It connects the village of Dzongla (4,830 metres (15,850 ft)) to the east and the village of Thagnak (4,700 metres (15,400 ft)) to the west.

After reaching Himalayas he laid down a New route towards North to travel across Golden Himalayan Mountain Range in to Tibet using his soldiers , and had closed an unusable older route as mentioned in Periya Puranam 55

“பொன்மலை புலி வென்று ஓங்கப்
புதுமளையிடுத்துப்
பொற்றும் அந்நெறி வழியேயாக
அயல் வழி அடைத்த சோழன்”
– பெரியபுராணம் 55

இலங்குவோர் கரிகால்பெருவளத்தோன் வன்திரள் புலி 

இமயமால் வரைமேல் வைக்க வெகுவோன்”
பெரிய புராணம் 25 Periya Puranam.25.

பகைவிலக் கியதிப்

பயங்கெழு மலையென

இமையவர் உறையும் சிமயப் பீடர்த்தலைக்

கொடுவரி ஒற்றிக் கொள்கையிற்” . Silappadhikaram.

செண்டு கொண்டுகரி காலனொரு காலி னிம

சிமய மால்வரை திரித்தருளி மீள வதனைப்

பண்டு நின்றபடி நிற்கவிது வென்று முதுகிற்

பாய்பு லிக்குறிபொ றித்தது மறித்த

பொழுதே.”- Kalingathipparani

The Chola King had Engraved his “Tiger” Symbol marking his Victorious Expedition to Himalayas in its rock at high Altitude. Since many soldiers along with him in the himalayan conquest were from Chera and from Pandya kingdoms , he engraved Bow Arrow and Fish symbols of Chera and Pandya too along side of his Tiger Symbol in Himalayan Rocks.

There was mention of 3 friendly kingdoms in Silapathikaram that came on his way namely Vajra Desam with Kosambi as it Capital in areas of Vanga (bangladesh) , Magadha Naadu and Avanthi naadu with Ujjain as its capital.

All these Three kings had welcomed Karikala Cholan and had gifted him with most valuable things Gold jewels and rathnas , Vajra King Presented him with Muthu Pandhal (Pearl Jewels) , and Magadha King had presented him with Patti Mandapam , Avanthi King had gifted him with Traditional Glittering Hanging Door Decorations made of Navarathnas as mentioned in Silapathikaram , it also says that karikalan on returning to his kingdom had showcased all the three rare gifts in “Chithira Mandapam” for his people to witness its beauty in Poompuhar Pattinam. https://www.quora.com/Which-Tamil-kings-went-on-Himalayan-expeditions-and-engraved-or-planted-the-victorious-symbols-of-their-flag-on-Himalayan-mountains?top_ans=102753057

In Tibetan language, La means Pass. But this is Chola Pass, not Cho La Pass as erroneously written; ‘Chola’ La, if you like. It is to be noted that the mountain range is called Chola Range, not Cho La range. … In fact, ‘Chozha’ is the right word, not Chola. The Tamil letter zha (ழ) is a tongue-twister, unique to Tamil.

According to the Imperial Gazetteer of India Vol. 10, page 327 New edition 1908, earlier edition 1885 – “The Chola Pass is in the Chola Range of Eastern Himalayas, 14,500 ft. above the sea, situated in 27º 25’ N and 88º 49’ E, leading from Sikkim State to the Chumbi Valley in Tibet. The Chola range, which is loftier than the Singalila, leaves the main chain at Dongkya Mountain.” In the map of Sikkim (http://dsal.uchicago.edu/reference/gaz_atlas_1909), Chola Pass is clearly marked. Also Jelap La but not the now-famous Natu La pass. Despite my Himalayan efforts I couldn’t download this map. Nathu La is itself situated in the Eastern Chola Range. Most of the passes that help cross Himalayas are closed for almost nine months but Chola Pass is open for six months, says the gazetteer of 1909.

… Cho La is mentioned in a Sikkim map of a 1979 tourism folder . Source provided below.

https://tripurachronicle.in/ArticleDetails.aspx?WhatId=85