BIALYSTOK, Poland: The elegant Nepali woman, clad in a pink sari, beamed as the tall German man strolled by.
They both called out a greeting: "Saluton!" Then they launched into an animated discussion in Esperanto, a language created from scratch more than a century ago in an attempt to foster global harmony.
Some 2,000 Esperanto-speakers from 63 nations spent last week in Bialystok at an anniversary congress marking the 1859 birth in this northeastern Polish city of their founding father, Ludwik Zamenhof.
It is hard to say how many people speak Esperanto, which has devotees worldwide but never achieved the breakthrough Zamenhof dreamed of. "There are no official statistics, and estimates range from the hundreds of thousands through to two million. But I think to be honest under a million is more realistic," said Jaroslaw Parzyszek, 46, head of the Bialystok-based Zamenhof Foundation.
For users, Esperanto is more than a language. It offered global social networking well before the birth of the Internet.
"It's about contact with people," said Indu Devi Thapaliya, 45, from Nepal.
She started learning in 1990 from a Pole in Nepal's capital Kathmandu. She now teaches it, and was attending her fifth annual congress. The Bialystok edition, which wrapped up on Saturday, was the 94th.
Esperanto's seeds were planted in the 1870s. It grew out of an idealism that saw its founder nominated for the Nobel Peace Prize 13 times before his death in 1917.
Bialystok was then in the Russian empire, in a region inhabited by speakers of Polish, Yiddish, German, Belarussian and Russian.
Zamenhof, who was Jewish, was brought up by Russian and Yiddish-speaking parents but later raised his own children as Polish-speakers.
"When he was young, my grandfather saw the hostility among people who couldn't understand one another. And he said to himself: 'If these people could understand one another, they could understand the reason for their differences, and appreciate these differences'," said Polish-born Louis-Christophe Zaleski-Zamenhof, 84, who lives in France.
Zamenhof devised the easy-to-learn tongue from elements of Romance, Germanic and Slavic languages and a dash of Latin and Greek.
He tested it on fellow students while studying ophthalmology, and published it in 1887. "Esperanto" was his writer's pseudonym, a reference to the word "hope".
Francois Randin, 58, from Switzerland said he fell in love with Esperanto 15 years ago. "The beauty of Esperanto is that it's so simple - not simplistic - yet so rich," said Randin, sporting a necklace with its global symbol, a five-pointed green star.
The language is regulated by the 45-member Akademio de Esperanto, which works to keep it up to date via suggestions from speakers.
"Esperanto is a tool to meet people of every nationality and culture. It makes us all dual nationals by definition," said Randin, noting that he traveled around China thanks to Esperanto contacts in the Asian nation.
Esperanto is sometimes criticized for being too European-rooted, but Thapaliya said that was no problem.
"And it's much easier than English," she added.
The issue of English's global clout sparks debate among Esperanto-speakers. "Esperanto is neutral, unlike English which creates inequality between people who are born anglophone and those who learn it," Zaleski-Zamenhof said, recalling regular misunderstandings when doing business in English.
Esperanto fans are used to the kooky image many outsiders have of them.
"I speak it because I find it useful, not because I have any ideological link to it in any way," said Rolf Fantom, 28, who was raised in an Esperanto-speaking household in Britain.
"You have a lot of strong-minded people who've taken it from being a completely made-up language through to, 120 years later, hundreds of thousands of people speaking it," he said. "I can't see a way for it to become the international language because English has filled that role already. But does it have a future as a language, a culture and an internationalist entity? Yes it does!"