Sikhs are a very small community of about 25 million spread over all the world.
Why have they spread throughout the world?
There is a very interesting story about this.
Here it is.
Guru Nanak travelled extensively to spread the message of love, compassion and humanity, and to profess the purpose of human life on Earth. Nanak had gained immense popularity and was highly respected by all sects of society. The news of his visit to any village would reach much before his arrival, and people used to prepare their villages in advance to welcome him.
But, in one of his journeys, Nanak along with his companion and disciple Mardana were getting into a village to have a different experience. The natives of this place were cold, haughty, and disdainful. The village was headed by cruel landlords and hypocritical priests who did not like a holy man visiting them.
They let Nanak into their village as per the prevalent customs, but showed their arrogance and bragging in one way or the other to indicate that he was an unwelcome guest, and that he should leave their village.
Nanak spent some time with them in an attempt to teach them the truth, but realized that the natives were not willing to change at all. So, he decided to leave from there. He used to bless the people of every village before moving on to the next.
Keeping this tradition upon leaving the village, he raised his hand and blessed the villagers, and said, “Vasde raho” (may you stay and prosper here).
Having received an extremely cold treatment from the villagers, Mardana was astonished at Nanak’s blessings. But he had no clue as to why Nanak wished they stay there.
Further on their journey, they arrived in another village. The natives here were simple, loving, kind, and gracious in their behavior. Every day, the villagers would get together and listen to Nanak’s lessons of wisdom. Very keenly involved, they would ask Nanak their questions, and they learned from him how they could transform their lives to overcome their sufferings and embrace excellence.
Nanak spent a few days with them. When he realized his purpose had been served, he bid farewell to the village. While leaving, in his customary style, Nanak raised his hand to bless the villagers, and said, “Ujad Jao” (may you get displaced).
Hearing Nanak’s benediction, Mardana was completely baffled. Unable to control his curiosity, he asked, “O Nanak, you blessed those who ill-treated us to stay, and these people who have been so nice to us, you are blessing them to get displaced. Why? I cannot understand the point.”
Nanak gave a discerning reply, “The natives of the previous village are conceited. Their towering ego has closed their minds to new insights, so there isn’t even a chance for transformation. They do not possess good values and morals. It is better they stay within their village, so that, their egoism doesn’t affect others. Contrarily, people of this village are good and they carry great values. If they are displaced, they will go to other places. Wherever they will go, they will enrich others with their high values and character. They will bring positivity among people. They have the potential to change the society for betterment.”
Mardana, bemused at Nanak’s enlightened vision, fell on his feet and thanked God for he had the most wonderful teacher one could ever have.
Hence many Sikhs have left Punjab and moved on to many countries all over. It is joked that you may even find a Sikh on Mars.
https://www.sikhdharma.org/guru-nanak-and-the-two-villages/